Rub the steaks with olive oil and season on both sides with salt and pepper. Put aside.
Meanwhile, put garlic, Dijon mustard, lemon juice, black olives, green olives, and half of olive oil in food processor or mini-chopper. Pulse until olives are coarsely chopped, then blend at full speed for a few seconds to combine all ingredients.
Remove from processor and stir in olive oil.
Heat the grill pan for about 5 minutes. Cook the steaks for 5 minutes on each side or until done to your liking.
Remove the steaks from the pan and let rest about 5 minutes, then serve with olive sauce spooned over the top.