1. Preheat grill to 350° to 400° (medium-high) heat. Grill pepper, covered with grill lid, 3 to 4 minutes or until pepper looks blistered, turning once. Place pepper in a large zip-top plastic freezer bag; seal and let stand 10 minutes to loosen skins. Peel pepper; remove and discard seeds. Coarsely chop.
2. Combine pepper, cucumber, next 4 ingredients, 2 Tbsp. lime juice, and 2 Tbsp. olive oil in a bowl.
3. Whisk together seafood seasoning and remaining 1 Tbsp. lime juice, and 2 Tbsp. olive oil in a large shallow dish or zip-top plastic freezer bag; add fish, turning to coat. Cover or seal, and chill 5 minutes, turning once. Remove fish from marinade, discarding marinade.
4. Grill fish, covered with grill lid, 3 to 4 minutes on each side or just until fish begins to flake when poked with the tip of a sharp knife and is opaque in center. Cool 5 minutes. Flake fish into bite-size pieces.
5. Serve fish and salsa in warm tortillas with lime wedges.
Note: We tested with Weber Mango Lime Seafood Seasoning.