Consider all that can go wrong with eggs sunny-side up.

They can be under-cooked, leaving the whites slimy. They can be over-cooked, leaving the yolks hard. They can be cooked on too high a heat, leaving the edges of the whites brown and chewy. Or the delicate yellow yolks might break, ruining the whole “sunny” effect.

This is why I appreciate a dependable, perfect-every-time breakfast place like Q Street Diner in South Portland.

When I ate there recently, my two eggs were a perfect version of sunny-side up. The giant yolks were intact, perfect for dipping into with the extra-thick slices of toast. The whites were also perfect, firm but not burnt. Over the years, I’ve never had a bad egg at Q Street.

My meal came with corned beef hash and home fries. The hash had minced corned beef and tiny potatoes, and wasn’t a bit greasy. The cook had left them on the grill just long enough to create a thin crust on the hash, but none of it was overcooked. The home fries were crisp, and there were a lot of them.

The entire thing — two eggs, two slices of toast, hash and home fries — cost $6.25. I could have gotten hash browns instead of home fries for the same price.

My dining companion ordered the hash browns, which were like two giant tater tots. She also got bacon, which was nice and crisp — no hint of the rubbery texture bacon sometimes gets when cooked improperly.

The two-egg breakfast with bacon or sausage (instead of hash) is $5.95 at Q Street. An egg-and-cheese sandwich on an English muffin is $2.50, while the same sandwich with bacon, ham or sausage is $2.95.

Eating at Q Street reminded me of all the things I love about an old-fashioned diner. In the ideal world of diners, the food is always good, so when you get “the usual,” you know you won’t be disappointed.

The diner concept is also about comfort and ease. Q Street is located in a simple cinder-block building behind Shaw’s supermarket in the Mill Creek business district. It’s big for a diner and the layout is spread out, so you don’t feel crammed in.

There’s a large room when you first come in, a counter area, and then a long, narrower seating area that ends with seats in the front window. There are always weekly newspapers to read and a table with puzzles, games and crayons for the kiddies.

Although I’m a creature of habit, I have tried other Q Street favorites before. I’ve had the apple pancakes ($7.25), which are giant, fluffy and full of chunks of apple and cinnamon. You won’t need to eat the rest of the day.

The breakfast menu also includes three-egg scrambles, starting at $6.95, and four-egg omelets, starting at $6.95. There are grilled breakfast tortillas, made with three eggs and various fillings, starting at $5.50.

Besides all the breakfast choices, Q Street’s menu also includes a large variety of lunch dishes, including burgers, chicken sandwiches, hot subs and sandwiches, and cold sandwiches and roll-ups.

After you’re full from your big breakfast (or lunch), it’s just a quick walk from Q Street to a couple of nice strolling spots — Mill Creek Park with its duck pond, or Thomas Knight Park along the harbor and under the Casco Bay Bridge.

The Features staff of The Portland Press Herald/Maine Sunday Telegram anonymously samples meals for about $7.