To prepare sauce, cut bell pepper in half lengthwise; discard seeds and membranes. Place bell pepper and tomato halves, skin sides up, on a foil-lined baking sheet; flatten peppers with hand. Broil for 12 minutes or until peppers blacken. Place peppers and tomatoes in a zip-top plastic bag; seal. Let stand 15 minutes. Peel peppers and tomatoes. Place peppers, tomatoes, almonds, and next 7 ingredients (through 2 chopped garlic cloves) in a food processor, and process until smooth.
Reduce oven temperature to 400°.
To prepare relish, combine olives and next 6 ingredients (through 2 minced garlic cloves) in a small bowl.
To prepare fish, combine wine and next 6 ingredients (through 2 minced garlic cloves) in a large zip-top plastic bag. Add fillets to bag; seal and marinate in refrigerator 30 minutes, turning bag occasionally.
Remove fillets from bag; discard marinade. Place fillets on a jelly-roll pan coated with cooking spray. Sprinkle fillets with 1/2 teaspoon salt. Bake at 400° for 15 minutes or until fish flakes easily when tested with a fork or until desired degree of doneness. Serve with romesco sauce and olive relish. Garnish with oregano sprigs, if desired.