In a large pot add the olive oil and sauté the spring onion at medium to low
heat for about 2 minutes.
Add the mushrooms and leek and a bit of salt continue sautéing for another 3-4 minutes.
Add the tomato and the tomato paste and stir, and then add just enough hot water to partially cover the vegetables.
Cover the pot and simmer (it should not be boiling for about 30-35 minutes). It should not be watery.
Remove from heat and let it cool to room temperature.
Sprinkle with parsley and freshly ground pepper and serve.