Carrot and Leek soup

sliced leeks (about 3 leeks, white and light green part only)

sliced carrots (about 10 medium carrots)

red lentils, rinsed and picked over

x 1 liter cartons of low sodium organic chicken stock or veg. stock

tb. unsalted butter

olive oil

salt & pepper

bunch of scallions

creme fraiche