Purée of Onion Soup with Thyme Leaves

• 450 g chopped onions
• 140 g chopped potatoes
• 45 g

Peel and chop the onions and potatoes into small dice. Measure. Melt the butter in a heavy saucepan. As soon as it foams, add the onions and potatoes; stir until they are well coated with butter. Add the thyme leaves, season with salt and freshly ground pepper, cover with a paper lid (to keep in the steam) and the saucepan lid, and sweat on a low heat for approximately 10 minutes. The potatoes