Make a shallow cross-cut on the tomatoes. Thinly slice the onion. Cut the potatoes into small bite-sized pieces and soak them in water, then drain.

Boil water in a pot and briefly blanch the tomatoes. Transfer to cold water, peel the skin, cut in half, remove the stem and seeds, then dice into 1cm cubes.

In a separate pot, heat butter over medium heat. Add onion and potatoes, sauté for about 5 minutes until translucent. Add tomatoes, water, and consomme, cover, and simmer on low heat for about 10 minutes until potatoes are tender. Let cool slightly.

Blend the mixture in a blender until smooth. Strain through a sieve back into the pot. Add milk and fresh cream, heat over medium heat while stirring until just before boiling. Adjust seasoning with salt.