Cooking the egg to the right consistency is key. I like my yolk a little runny, so I cook it for about 1-2 minutes per side. If you do not like your yolk runny, then I recommend cooking it for about three minutes per side.  My other tip for making the best egg sandwich is choosing the cheese. A soft feta Bulgarian or Turkish cheese is perfect. I do not recommend using dried Greek cheese, as it will not create a smooth and creamy texture to spread on the toast.