Red Lentil Soup

2 cups split red lentils, rinsed several times
1 tablespoon turmeric
4 tablespoons butter
salt
1 large onion, finely diced (2 cups)
2 teaspoons ground cumin
1 1/2 teaspoons mustard seed or 1 tsp ground mustard
1 cup chopped cilantro
juice of 3 limes
1 large bunch spinach, chopped small
1 cup cooked rice
6 tablespoons yogurt

Put the lentils in a soup pot with 2 1/2 quarts water, the turmeric, 1 tablespoon of the butter, and 1 tablespoon salt. Bring to a boil, then lower the heat and simmer, covered, until the lentils are soft and falling apart, about 20 minutes. Puree for a smooth and nicer-looking soup. (An immersion blender is a great plus here.)

While the soup is cooking, prepare the onion flavoring: In a medium skillet over low heat, cook the onion in 2 tablespoons of the remaining butter with the cumin and mustard, stirring occasionally. When soft, about the time the lentils are cooked or after 15 minutes, add the cilantro and cook for a minute more. Add the onion mixture to the soup, then add the juice of 2 limes. Taste, then add more if needed to bring up the flavors. The soup should be a tad sour.

Just before serving, add then last tablespoon of butter to a wide skillet. When foamy, add the spinach, sprinkle with salt, and cook just long enough to wilt.

If the rice is warm, place a spoonful in each bowl. If it's leftover rice, add it to the soup and let it heat through for a minute. Serve the soup, divide the spinach among the bowls, and swirl in a spoonful of yogurt.

Serves 4.