The leaves of the black locust contain toxins, which is why they should only be eaten properly cooked! If you are not familiar with safe preparation, you should not experiment. Vomiting is only one of the consequences of eating incorrectly prepared robinia leaves. Nevertheless, black locust has its place in the wild vegetable kitchen and as famine food. The leaves can be used to make a kind of spinach. The toxins contained are heat-labile and water-soluble, so that they can be eliminated by sufficient watering and/or cooking.
More important for the kitchen are the non-toxic and wonderfully fragrant black locust flowers.