This is an easy weeknight, yet guest-worthy, real-food meal! Capers are optional. Serve over zoodles, spaghetti squash or alongside roasted vegetables and caprese salad.
Heat Instant Pot on saute setting until display reads "HOT". In the meantime, prepare chicken pieces: dredge in tapioca flour, shake excess and salt and pepper each piece.
Once Instant Pot reads "hot," add oil and allow to heat. Cook chicken pieces 2 to 3 minutes per side to brown (work in batches). Remove all chicken to a plate.
Melt butter in Instant Pot, then add chopped onion and cook about 5 minutes until soft. Return chicken pieces to Instant Pot (on top of onion). Arrange lemon slices over chicken. Pour white wine and water into Instant Pot. Add capers, if using.
Set Instant Pot on Manual, HP (high pressure) for 2 minutes. Allow Natural Pressure Release for 5 minutes, then carefully release remaining pressure, sprinkle with parsley and serve.