In a large bowl, combine 2 cups of drained, overcooked lentils, 2 cups of chopped/mashed sweet potato, the sautéed vegetables, 1 cup slightly fork-mashed black beans, ½ cup oat flour, thyme, and salt. Stir well, the mixture should be very thick (if it seems dry, add vegetable stock, 1 tbsp at a time, until the mixture is just moist. If the mixture is too soft, add more oat flour. Taste and adjust the salt if necessary.