Place onion, garlic, red bell pepper, lemon juice, olive oil, sea salt, piri piri seasoning and black pepper in blender container. Process until smooth.
Place chicken pieces in medium bowl and add marinade.
Toss to coat well, cover and marinate 4 hours or up to overnight.
Grill chicken on oiled grates over medium heat, turning often, for 15-20 minutes, or until internal temperature reaches 165°F.