1. In a bowl, mix peppers, olives, yogurt, olive oil, lemon juice, garlic, turmeric, and cayenne to coat; add salt to taste. Cover and chill at least 1 hour and up to 1 day (see notes).
2. With a serrated knife, slice about 1 inch off top of loaf. With the knife, hollow out center of loaf, leaving a shell about 1 inch thick. Cut top slice and bread from middle into chunks.
3. Spread hummus in bottom of bread bowl. Top with pepper mixture and feta. Set on a platter and surround with reserved bread chunks for dipping.