Preheat oven to 350 degrees F.
Spread the pecans on a baking sheet and bake until it turns golden and fragrant from 4 to 5 minutes.
Mix together the mayonnaise, buttermilk, lemon juice, pepper, dill, tarragon and garlic powder and set aside.
Place a nonstick pan over medium-high heat.
Add the chicken and cook from 4 to 5 minutes while turning only once, until golden-brown and heated through.
Add the corn and cook and stir for 2 minutes, until it starts to brown.
Mix in a bowl the lettuce and onion with the reserved pecans and corn; and arrange on the serving plate.
Add the chicken on top and drizzle with the Ranch dressing.