For the sauce. In the same pan you cooked the chicken in, wipe it out with a paper towel, melt 2 tbsp butter on medium heat, add the minced garlic, onion, saute until transparent, add wine, capers and lemon juice. Salt and pepper to your taste (capers tend to be salty). Boil over high heat until sauce is reduced to half the amount, swirl in the remainder of the butter to combine. Remove from heat.