Heat grill pan or nonstick skillet over high heat. Spray the pan with cooking spray. Place fish on grill, season with salt and pepper and cook 5 minutes on each side, until opaque.
Arrange lettuce leaves on a platter. Place jalapeno in a food processor with cilantro, mint, mustard and vinegar. Turn processor on and stream in oil. Season sauce with salt and pepper.
Take the fish off grill and place on a serving plate. Break the fish into chunks and squeeze lime juice over fish. Add a few dashes hot sauce to the fish.
Pile fish in lettuce leaves and top with sauce and chopped red onions.