It looks like a trend -- cooking chicken with mustard

Dijon mustard was the popular ingredient in this year's 35th National Chicken Cooking Contest. Seven contestants used it with fine results. Garlic was the No. 1 seasoning, and as 300 pounds of chicken were roasted, broiled, and fried in the air-conditioned auditorium of the Birmingham Civic Center, the aroma was truly wonderful.

Fifty-one recipes using all kinds of herbs and spices, sauces and seasonings, all cooking at once evokes a cacophonous image, but somehow it all managed to smell great.

They did it all well, these representatives from 50 states and the District of Columbia, in spite of television cameras, people who stopped to watch and ask questions, a band playing, and distractions enough to rattle even the coolest of cooks.

The chicken was subjected to every traditional treatment plus a few new ones, resulting in dishes that ranged from a whole chicken basted in purple plum jelly to the inevitable peanut-butter concoction (which incidentally, has never won yet) and to a marvelous combination of pecans and Dijon mustard.

Karen Johnson of Wichita, Kan., who says she sets aside a day each week to experiment in the kitchen, was the first-place $10,000 winner with a simple recipe for boned chicken breasts seasoned with lime butter, chives, and dill weed.

She almost didn't come. A shy woman, she needed her husband's moral support, and when something came up that might have prevented his coming, she nearly canceled out. She entered only one recipe, Chicken with Lime Butter, which the judges described as ''a new way to look at chicken; simple, straightforward, inexpensive, and absolutely delicious.''

The second-place winner is the wife of former governor Winfield Dunn of Tennessee. He stood by her the whole time, cheering her on as she earned $4,000.

''I never do this,'' Betty Dunn admitted, as she pounded ever so gently on the chicken with a heavy metal mallet. ''This is Winfield's part of the job.''

He kept encouraging her, telling her not to be afraid to whack it hard. The Dunns had cooked this dish together at a charity event in Nashville last year, and Pierre Franey,the New York Times food editor who was a judge in Nashville as well as at this year's event in Baltimore said, ''I swear I didn't recognize it as being the same dish that won the other contest.''

Betty, who says she never was any good at frying chicken, loves cooking and ''would rather try a new recipe than anything.''

Her prize-winning recipe, Pecan Chicken with Dijon Sauce, can be made successfully with walnuts, using walnut oil instead of safflower oil.

The third-place winner, Pamela Stross of Boulder, Colo., had just taken her bar examination the previous week and is starting a new job. At 26, Pamela has great stage presence, and says she likes cooking ''for an audience.

''It's no fun to cook just for yourself. I like a quick, efficient dish that looks as though you went to a tremendous amount of trouble to make it. That's why I like chicken . . . it's so predictable.''

Her Rainbow Chicken Salad was arranged on a large platter, the slices of chicken alternated with slices of avocado, grapefruit, onion, and oranges. Again , the Dijon mustard gave a special life to the homemade mayonnaise.

The purplish-brown Plum Sweet and Spicy Chicken was fourth-place winner, the invention of Joan McCormick of Tabb, Va., who has been a contestant once before in the national contest and three times in the Delmarva Chicken Cooking Contest, when Delaware, Maryland, and Virginia used to send their best cooks to compete.

Joan has published two cookbooks and writes a cooking column. She went home from Birmingham with an extra $2,000 in her purse.

Dried prunes and bananas won fifth place for Emily Kosak of Brown Deer, Wis. Called Latin American Chicken, it uses quartered chickens fried to a golden brown and covered with a fruity sauce. A retired drill press operator, Emily sent in 20 recipes; one won her $1,000.

The National Chicken Cooking Contest is not annual any more.It goes now on an every-other-year schedule, and the next contest will be in Asheville, N.C., in the spring of 1985.

But entries may be submitted any time before the Dec. 31, 1984 deadline. Just write name, address, and telephone number on the front of each recipe and mail to Chicken Contest, Box 28158, Central Station, Washington, D.C. 20005.

For a cookbook containing all the 51 finalists' recipes and other recipes and chicken information, send $1.50, check or money order, to Chicken Cookbook, Department NBC, Box 307, Coventry, Conn. 06238. Chicken with Lime Butter 6 broiler-fryer chicken breast halves, boned, skinned 1/2 teaspoon salt 1/2 teaspoon pepper 1/3 cup cooking oil 1 lime, juiced 8 tablespoons butter 1/2 teaspoon chives, minced 1/2 teaspoon dill weed

Sprinkle chicken on both sides with salt and pepper. Place oil in large frying pan and heat to medium temperature.

Add chicken and saute about 4 minutes, or until lightly brown. Turn it, cover and reduce heat to low. Cook 10 minutes, or until fork can be inserted easily.

Remove chicken and keep warm. Drain off oil and discard. In same frypan, add lime juice and cook over low heat until juice begins to bubble.

Add butter, stirring, until it becomes opaque and forms a thickened sauce. Stir in chives and dill weed. Spoon sauce over chicken. Makes 6 servings. Pecan Chicken with Dijon Sauce 2 whole broiler-fryer chicken breasts, halved, boned, skinned 12 tablespoons butter, divided 4 tablespoons Dijon mustard, divided 6 ounces pecans, finely ground 2 tablespoons safflower oil 2/3 cup sour cream 1 teaspoon salt 1/4 teaspoon freshly ground pepper

Place chicken between 2 pieces of wax paper. On hard surface with meat mallet or similar flattening utensil, pound to 1/4-inch thickness.

In small saucepan, place 8 tablespoons of butter and melt over medium heat. With wire whisk, beat in 3 tablespoons of mustard until well blended.

Place pecans in shallow pan. Dip chicken, one piece at a time, first in butter-mustard mixture, then in pecans, dredging to coat on all sides.

In large frypan, add remaining butter and oil, and heat to medium temperature. Add chicken and saute about 3 minutes on each side, or until brown. Remove to baking pan and bake in 200 degree F. oven about 20 minutes, or until fork can be inserted easily.

Drain frypan and deglaze it with sour cream. Using wire whisk, add remaining mustard, salt, and pepper. For each serving, place chicken over small portion of sauce. Makes 4 servings. Rainbow Chicken Salad 2 whole broiler-fryer chicken breasts 2 cups water 1 teaspoon salt 1/4 teaspoon pepper 1 head romaine lettuce 2 avocadoes, peeled, sliced lengthwise 2 grapefruit, peeled, seeded, sliced into sections 1 lemon, juiced 4 navel oranges, peeled, seeded, sliced into sections 1 sweet red onion, sliced Orange-Mustard Mayonnaise

Place chicken in deep saucepan. Add water, salt, and pepper. Cover and simmer about 45 minutes, or until fork can be inserted easily. Cool.

Separate meat from bones and skin. Reserve broth for later use if desired. Cut chicken into thin strips and set aside.

On large platter, arrange leaves of washed romaine with stalks toward center of platter and tips outward.

Alternate slices of avocado and grapefruit in outer ring, sprinkle with lemon juice. Alternate orange and onion slices for an inner ring. In the center, arrange chicken.

Pour Orange-Mustard Mayonnaise over chicken and serve remainder in separate bowl. Makes 4 servings. Orange-Mustard Mayonnaise 2 egg yolks 2 teaspoons Dijon mustard 1 teaspoon lemon juice 1 cup olive oil Grated peel of 1 orange Juice from 1/2 orange Salt Pepper

In medium bowl, beat egg yolks together with Dijon mustard and lemon juice.

Add olive oil, very slowly in thin stream, until mixture thickens. Add grated peel and juice. Add salt and pepper as desired. Plum Sweet and Spicy Chicken 1/2 teaspoon white pepper 1/2 teaspoon ground ginger 1/2 teaspoon ground cinnamon 1/4 teaspoon ground cloves 1 whole broiler-fryer chicken 1/4 cup soy sauce, divided 2 tablespoons honey 1/2 cup plum jelly 2 teaspoons sugar 2 teaspoons vinegar 1/4 cup chutney

Mix together white pepper, ginger, cinnamon, and cloves. Rub inside of chicken with half of spice mixture.

To remaining spice mixture, stir in 1 tablespoon of the soy sauce and rub on outside of chicken. Place in refrigerator and let stand 1 hour.

Remove chicken from refrigerator and place, breast side up, on rack in a wok over 2 inches of boiling water. Cover; steam 1 hour.

Remove chicken to shallow baking pan. Bake in 375 degree F. oven about 15 minutes, or until leg moves freely when lifted or twisted.

In shallow dish, mix remaining soy sauce and honey and brush over chicken. Mix together plum jelly, sugar, vinegar, and chutney and rub on chicken.

Return chicken to oven and bake at 450 degrees F. for about 10 minutes, or until chicken is brown and fork can be inserted in chicken with ease. Makes 4 servings.