Butter the bread slices with ¾ to 1 tablespoon butter and toast them on a hot skillet until golden and crisp. You may also toast them in a toaster.
Spread mayonnaise or Greek yogurt or cheese spread over the toasted bread. Layer the bread with veggies,
Melt the rest of the butter in the pan.
Break the egg to a bowl or over the melted butter in the pan directly. Cook on a medium heat until the the eggs are partially.
Turn them over and cook on the other side just until done and not overcooked. Sprinkle black pepper and salt. Place cheese slice on the hot eggs if you want.
Remove it to the prepares bread. Add more veggies if you want. Cover with another slice of bread.
Serve the fried egg sandwich immediately.