Put 1 and 1/2 cup red lentils into a pot with 6 cups of water, 1 bay leaf, 1 cinnamon stick, 1 tsp. turmeric, and 2 tsp. of salt. Bring to a boil, then simmer over low heat for 25 minutes, or until the lentils are a muted amber color and the mixture is the consistency of a thick porridge.
2 cups 1" cauliflower florets
2 large carrots, peeled and roughly chopped
1 cup roughly chopped cabbage
2 cups Yukon gold potatoes, cut into 2" chunks
Simmer until potatoes are tender, about 30 minutes.
Meanwhile, heat 3 T. olive oil in a large saute pan. Add 1 tsp. mustard seed, cover, and cook until the seeds pop, about 30 seconds. Reduce heat and add 1 tsp. cumin, 2 T. peeled, minced ginger, 2 T. minced garlic, 1 small serrano chile, finely chopped, and 2 cups minced onion. Saute until the onions begin to brown. Stir the mixture into the soup pot, season with salt and pepper, and serve in soup bowls, topped with chopped cilantro.