Do ahead: If you buy 2 whole breasts (unboned), the reserve after filleting should get you about enough stock for this recipe.
Mix oil, garlic, thyme, and pepper in airtight container.
Thoroughly submerse chicken in liquid.
Cover and refrigerate at least 24 hours.
May be cooked a variety of ways.
Pan frying is good, but a little dry. (I like microwave a lot, about 10-12 minutes. I'll put a slice of cabbage over the chicken just to help hold the heat in.)
Bring stock in pan to boil, add rices.
Cook 20-25 minutes.
Mix mushrooms and peas in 5 minutes before done.