Egg and Onion Sandwiches

• 1/2 cup finely chopped onion or green onion
• 1 tablespoon butter
• 1/2 cup finely chopped mushrooms
• Salt and freshly ground black pepper
• 4 hard-boiled eggs, finely chopped
• Mayonnaise, if needed
• Whole wheat or rye bread

Saute the onions in the butter for a few minutes, until just wilted and soft. Toss in the mushrooms and cook down with the onions for two to three minutes. Season with salt and pepper, let it cool, then toss with the hard-boiled eggs. Add a tiny bit of mayonnaise if the mixture needs binding. Spread this on whole-wheat or rye bread.