Roughly dice the cooked beetroot. Finely purée about two-thirds of it using an immersion blender, and cut the remaining third into bite-sized small cubes and set aside.

Peel and finely chop the onion and garlic. Pluck the thyme leaves from the sprigs. Heat the vegetable broth in a small pot and keep warm over low heat.

Heat the olive oil together with half of the butter (approx. 20 g) in a wide pot or casserole. Sauté the chopped onion and garlic over medium heat for about 2 to 3 minutes until translucent, without letting them brown.