Cut the onion into thin slices. Chop the garlic.
Heat the oil in a large frying pan and gently sauté the onion. Add the garlic and stir-fry for 30 seconds.
Add the lentils and vinegar, then stir for a minute. Add the kale and the stock.
Cover and cook for 5 minutes, then fold in the rice. Add more stock if it’s too dry - it should be moist but not have a sauce!
Warm through for a couple of minutes. Meanwhile, cut the beets into thin wedges.
Mix in some chopped herbs, then arrange the beetroot wedges on top and serve.