Grilled Steaks with Red Pepper Sauce

• 4 red bell pepper, quartered, stem and seeds removed
• 2 onion, sliced in rounds (¼ in.)
• 2 garlic clove
• olive oil, to drizzle and rub
• 910 gram beef flank steak
• ¼ teaspoon black pepper, ground
• ½ teaspoon salt

Red Pepper Sauce

• 115 g olive oil
• ½ teaspoon salt, to taste
• ¼ teaspoon black pepper, ground