Cucumber and Lettuce Vichyssoise - River Cottage

Ingredients

• 50g butter
• 2 leeks, trimmed (white and pale green part only), washed and sliced, or 1 large onion, sliced
• 1 large, floury potato (about 250g), peeled and cut into large
• 1 litre vegetable stock
• 2 cucumbers, peeled and cubed
• 2 Little Gem or butterhead lettuces, washed and shredded
• 3 tablespoons double cream or crème fraîche, plus a little extra
• Sea salt and freshly ground black pepper
• 4 tablespoons rapeseed or olive oil
• 4 slices of bread, crusts removed, cut into cubes
• Chopped chives