Add everything except the kale and flour to a saucepan and stir. Steam kale (or if you're making pasta, cook it in the boiling water before you add the pasta) for about 1-3 minutes, depending on how crunchy you like it. Remove and cut up in small pieces. Add to the sauce. Heat the sauce, and when it is fairly warm, start adding flour slowly, so that it doesn't clump. Whisk or stir constantly! When you have enough flour added, remove from heat, or serve immediately. I've found that this tends to burn quickly if left on a warm burner.
This is a recipe from Simply Vegan (Barbaras Kale Sauce).