Tomato Soup

1 quart of stock
1 tea-spoonful sugar
¹⁄₂ a tin of tomatoes
1 onion
1 tea-spoonful butter

Slice the onion. Fry it in the butter. Add it to the tomatoes. Heat them in a sauce-pan, and allow them to simmer for fifteen minutes. Rub through a sieve. Put to the stock. Season and add a lump of sugar. Heat. Serve with croûtons.