This gluten-free Mediterranean quiche is bright and briny thanks to the mix of sun-dried tomatoes and olives. The Manchego cheese adds a rich and nutty flavor. It's great for brunch, breakfast or dinner. Top with jarred salsa or bruschetta or a drizzle of hot sauce to counter the sweetness of the potatoes. If you have one, use a mandoline to slice the sweet potatoes into equal-size slices.