For a perfectly runny yolk, fry your sunny side up egg for about 2 to 3 minutes on medium-low heat. The key is to cook it gently so the whites set completely without overcooking the yolk. You’ll know it’s ready when the whites are firm but the yolk still looks jiggly and glossy. If you prefer the whites a bit more done, cover the pan for the last 30 seconds to help them set without affecting that golden, runny yolk.