Preheat the convection oven to 200 °C. Wash the sweet potatoes: leave the skin on and cut them into equal slices. If the sweet potatoes are very thick, you can also halve them lengthwise first. Mix them in a mixing bowl with a dash of olive oil and spread them over a baking tray lined with baking paper. Roast in the oven for 10 minutes while preparing the other vegetables.
Blanch the haricots verts in boiling water for a few minutes until al dente, then rinse with cold water.
Halve the avocado and remove the seed. Scoop out the flesh and cut the avocado into 6 equal segments. Add the haricot verts and avocado slices to the baking tray and drizzle with olive oil. Let them roast in the oven for another 10 minutes or until tender.
Stir in the oat crème fraîche and create a circle on the plates. Now prepare the seasonings. Cut the red pepper (to taste) into half rings, the garlic into small pieces or slices, and finely strip the fresh mint leaves.
Arrange the roasted vegetables and seasoning nicely on the plates and garnish with pistachios, lettuce, coarse sea salt and ground pepper.