Heat oil in a large pot and sauté the onion and garlic for about five minutes, until just barely golden. Add carrot and sweet potato and cook for three minutes. Add tomato cubes and cook for five minutes, stirring constantly.

Add water and seasonings and bring to a boil. Lower the flame and cook for 40 minutes over low flame until all the vegetables are soft.

With a hand blender, puree the soup until it is smooth. Taste and adjust seasonings. You can dilute with water if necessary. Bring to a boil again.

Heat one inch of oil in a frying pan and fry the leek strips until golden. Remove and place on absorbent paper towel.