Wash the vegetables well. Boil the beets (for about 40 minutes) and bake the sweet potatoes in a pyrex with 1-2 tbsp. olive oil (for about 40-50 minutes in a preheated oven at 180° C) until the vegetables become tender.
20 minutes before the sweet potatoes are ready, add the mushrooms to the pyrex with 1 tbsp. olive oil and stir at regular intervals.
Boil the barley for about 25-30 minutes.
Wash and sauté kale in 1 tbsp. oil for about 2 minutes.
Prepare the salad by adding the kale, the sweet potatoes, the beets, the mushrooms, and the barley. Add lemon, a little oil, onion flakes, garlic powder, salt, pepper and mayonnaise on top of it. Stir and enjoy!