Dice the onion, potato, carrot, celery, and garlic.
Blanch the tomatoes in boiling water, peel off the skin, and chop finely.
Heat olive oil in a pot and sauté the garlic and onion.
Add potato, carrot, celery, and tomato, and stir-fry together.
Once the vegetables are slightly cooked, add water and chicken stock and bring to a boil.
Simmer over medium-low heat until vegetables are tender.
Season with salt and pepper, sprinkle with parsley, and serve.