Preheat oven to 350°F (180°C).
Whisk eggs and sour cream. Set aside.
Spray 3-quart (3 L) baking dish with cooking spray. Pour in egg mixture. Bake in a 350 F (180°C) oven for 15 minutes or until almost set. Remove from oven and cool slightly while cooking the meat.
Cook ground turkey with onions and mushrooms until turkey is no longer pink. Drain excess liquid. Set aside.
Drizzle 1/2 cup (125 mL) picante sauce over egg mixture. Spoon turkey mixture and green beans over picante sauce and eggs.
Sprinkle cheese over turkey mixture. Bake in 350 F (180°C) oven for 10 to 15 minutes or until bubbly. Drizzle with remaining picante sauce. Serve each portion over lettuce, if desired.