Bengali spinach stir fry with crunchy lentils

from http://www.npr.org/2012/02/28/147038163/the-new-indian-pariahs-vegetarians
Sandip's mother, Reba Roy Chowdhury, still likes to make some vegetarian staples.

1 teaspoon mustard seed
1-2 dried red chilies
1-2 medium potatoes scrubbed and cut into small cubes
1 bunch spinach washed and chopped finely
1/2 cup frozen peas
1 tablespoon oil
Salt to taste
1 tablespoon bodi (small lentil dumplings available at Indian grocery stores) (Optional)

Heat the oil. When it is hot add the red chilies and mustard seed. As the seeds pop and the chilies darken, add the cubed potato. Fry the mixture until potatoes are lightly browned, then add the finely chopped spinach. Lower heat and cover for a couple of minutes. Water should come out of the spinach. Remove the cover and add the frozen peas. Stir the dish, and let the water dry up. The spinach should have a slightly fried look. Add salt and a pinch of sugar.

If you are using the bodis, fry them separately until they are crisp. Drain them on paper towels and then crumble them, sprinkling them on top of the stir fry.