Peel and finely dice the potatoes, carrots and onions. Place in cold water, heat and cook for 20 minutes. Puree with a little salt and olive oil in the brisk Lotte.
Pluck the spinach leaves from the stalks.
Boil the peas in salted water (5 to 20 minutes depending on the size). When the peas are almost cooked, add the spinach. Press the leaves under the surface with a wooden spoon. After 1 minute, drain the peas and spinach, drain and add to the soup with the stock cube. Reheat and season to taste.