Fried Egg, Cheddar and Crispy Onion Strings on Toast
A satisfying breakfast sandwich with a sunny-side-up egg, melted sharp cheddar, and shoestring-thin fried onions piled on buttered toast. The crispy onions add textural contrast and sweet-savory depth to this diner-style favorite.
Steps
Before you start
- Slice onion into thin matchsticks (use a knife or mandoline, watching your fingers carefully)
- Have all ingredients prepped and ready before you start cooking
- Use a non-stick skillet or cast iron for best results
Fry the onion strings
- Heat 1½ tablespoons (22 ml) of oil in an 8-inch (20 cm) non-stick skillet over medium-high heat.
- Once the oil is shimmering, carefully add the onion matchsticks, spreading them in a single layer.
- Let them sit undisturbed for 1 to 2 minutes so they begin to brown.
- Stir occasionally with a wooden spoon for the next 4 to 5 minutes, stirring and breaking apart any clumps as they crisp and turn golden brown.
- They will shrink significantly.
- Once deep golden and crispy, transfer to a paper towel–lined plate and season immediately with a small pinch of kosher salt.
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Ready when: Onion strings are deep golden brown and crispy throughout, not soft
Tip: Stir often toward the end so they crisp evenly without burning; don't walk away from this step
Toast the bread
- While the onion finishes, add ½ tablespoon (7 g) of butter to the same skillet over medium heat.
- Once the butter foams, add the bread slices and toast for 1 to 2 minutes per side until golden brown and crisp.
- Transfer to a plate.
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Ready when: Bread is golden brown and crispy on both sides
Tip: The skillet still has onion residue, which adds flavor; don't wipe it clean
Fry the egg
- Add the remaining ½ tablespoon (7 g) of butter to the skillet over medium heat.
- Once the butter is foaming and golden, gently crack the egg directly into the pan.
- Let it cook undisturbed for 2 to 3 minutes until the white is set and opaque but the yolk is still jiggly in the center.
- Season with a light pinch of kosher salt and black pepper.
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Ready when: Egg white is fully opaque and set; yolk jiggles when you gently shake the pan
Tip: Avoid moving the egg while cooking; this helps prevent the yolk from breaking and the white from tearing
Assemble the sandwich
- Place the toasted bread slices on a plate.
- Lay the cheddar slice on one piece of toast.
- Using a spatula, carefully transfer the fried egg onto the cheddar, breaking the yolk slightly so it begins to run into the cheese.
- Top with a generous handful of the crispy onion strings, then crown with the second slice of toast.
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Ready when: Sandwich is assembled and ready to eat
Tip: Serve immediately while the toast is warm and crispy and the yolk is still warm enough to flow into the cheese
Good to know
Tips
- Onion strings must be sliced very thin (about 1/8 inch / 3 mm wide) so they fry and crisp fully; thicker slices will remain chewy
- For extra richness, add a tiny dot of mayonnaise to one slice of toast before assembling
- If your skillet is not non-stick, use a small amount of extra butter to prevent sticking when frying the egg
- Keep the heat moderate to medium-high; too high risks burning the outside of the onion before the inside crisps
Storage & reheating
Best served fresh and warm. Leftovers are not recommended; frying egg and toast do not reheat well.
Substitutions
- sharp cheddar cheese → American cheese, muenster, or gruyère. Use the same weight. American cheese will melt most quickly; gruyère adds nutty depth
- yellow onion → white onion or sweet onion (such as Vidalia). Use the same weight. Sweet onions will be milder; white onion more assertive
- bread → English muffin, thick toast, or a buttered bun. Keep slices roughly the same size so they can become a sandwich
- large egg → 2 small eggs, fried together. Adjust cooking time by 1 to 2 minutes; yolk may break more easily with two eggs
