Preheat oven to 400⁰F.
Place red pepper in oven and roast until skin is charred all over, about 35 minutes. Remove from oven and let cool. Remove the skin.
Season sea bass with salt and pepper. Rub in the lemon juice.
Heat olive oil in an ovenproof sauté pan. Add fish, skin side up, and cook until well browned, about 3 to 5 minutes. Flip fish and turn off heat. Place pan in oven and bake until fish is flaky, about 5 to 7 minutes.
In a food processor, combine roasted red pepper, vinegar, garlic, olive oil, salt and pepper. Blend until emulsified.
To plate, spoon 1 tablespoon of puree on plate and lay each sea bass portion on top. Sauce can be prepared ahead and served warm, cold, or at room temperature