ASDA part of the Wal-Mart family

• 25g butter
• 1tbsp sunflower oil
• 1 medium onion, halved and thinly sliced
• 350g potato, peeled weight, sliced
• 800ml vegetable or chicken stock, made from a cube
• 2 x 85g packs Asda Watercress
• 300ml full fat milk
• 142ml single cream

1 Melt the butter in a saucepan with the oil. Add the onion and potato and stir until well-coated. Cover and cook over very low heat for 15 minutes, stirring occasionally, until the vegetables start to soften.

2 Add the stock, heat until boiling, then turn down and simmer, covered, for 15 minutes until the potato is tender.

3 Add most of the watercress and heat until the liquid simmers and leaves wilt – remove from heat, cool for 10 minutes.

4 Blitz in a blender and season. Add milk and cream, reheat and garnish with watercress sprigs.