Pat chicken dry. Season with salt and pepper.
Dredge chicken pieces in flour.
Heat avocado oil in frying or saute pan until hot. Reduce heat to medium.
Brown chicken pieces in the pan about 3 minutes until golden brown. Turn and cook another 2-3 minutes until cooked through.
Remove chicken from pan and place on a platter, Cover to keep warm.
Add chopped onions to the pan and cook about 2 minutes until softened.
Add one tablespoon of the broth and stir to loosen browned bits from the pan.
Add the mushrooms and saute about two minutes until onions are browned.
Add the rest of the broth, capers, and lemon juice.
Cook, stirring occasionally, for 5 minutes until mushrooms are cooked, and sauce thickens. Add more broth or a small amount of water if needed.
Return the chicken to the pan for 1-2 minutes to reheat. Serve chicken with the pan sauce.