For the sauce, whizz the capsicum (pepper) with the chilli, smoked paprika, lemon juice and 4 tablespoons extra virgin olive oil in a food processor or blender. When smooth, taste and season.
Trim the chicken thighs and bash out using the palm of your hand until the thighs are roughly even in thickness.
Place thighs in a bowl and cover with half the sauce. Marinate for a few minutes or up to 48 hours (if marinating for more than an hour keep refrigerated).
Heat a little oil in a pan and cook the thighs for 3-4 minutes on each side or until no longer pink in the middle. Serve thighs with the other half of the sauce.