In a large pot, heat olive oil and sauté onion, carrots and celery until soft, 7-8 minutes. Stir in minced garlic and cook, stirring, for 1 minute. Add a pinch of salt.
Stir in the tomatoes and cook for 3 minutes, breaking them up into small pieces with a wooden spoon. Add the cubed potato and cook, stirring, for 2 minutes. Stir in a pinch of salt.