• 2 small onions
• 1 teaspoon dry mustard
• 1 cup white sauce
• 1 tablespoon vinegar
• 1 tablespoon sugar
• Salt
• 2 tablespoon water

Chop onion fine. Cover with boiling water, let stand one hour. Drain and rub onion through sieve. Make white sauce, add onion. Add salt, mustard and vinegar. Carmelize sugar and water, add to' sauce.