Preheat oven to 400°F (200°C) and gather all ingredients and equipment.
Slice red bell peppers, toss with olive oil, salt, and pepper, then spread on a baking sheet.
Roast peppers for about 20 minutes until softened and lightly charred.
Let roasted peppers cool slightly, then blend with garlic, lemon juice, olive oil, salt, and pepper until smooth.
Heat olive oil in a skillet over medium heat.
Season tilapia fillets with salt and pepper, then cook in the skillet for 3-4 minutes per side until golden brown.
Pour the roasted pepper sauce over the cooked tilapia and simmer for 1-2 minutes to combine flavors.
Garnish with fresh basil or red pepper flakes, if desired, before serving.