Indian Spinach with Potatoes

I've been eating lots of spinach and potatoes this week, and this is one of the recipes that I tried. It comes from Winter Harvest Cookbook by Lane Morgan, published in 2010. It's an excellent resource for seasonal cooks and if you haven't checked it out yet—do so! It's definitely one of my new favorites. The author writes of this recipe: "This is quick and good. If you boil the potatoes beforehand, you can have dinner on the table in about 10 minutes." He suggests serving with a carrot curry and a raita for for a "beautiful and nutritious" vegetarian meal.

Indian Spinach with Potatoes
Serves 4 to 6

Ingredients
2 pounds boiled peeled potatoes
1 pound fresh spinach
¼ cup peanut oil or other light oil
1-inch piece fresh ginger, peeled and sliced thin
1 teaspoon mustard seed
1 teaspoon ground cumin
red pepper flakes (optional)
1 teaspoon turmeric
½ teaspoon chili powder
1 teaspoon salt, or to taste

Directions
Cut the potatoes into cubes. You should have about 4 cups. Chop spinach coarsely. Heat oil in a large saucepan, add onion, garlic, and fresh ginger, and sauté briefly. Combine mustard seed, cumin, red pepper flakes (if used), turmeric, and chili powder. Add to saucepan, stir well, and cook mixture over gentle heat until onion is soft. Add potatoes and stir gently to coat them with spices. Add spinach in handfuls. Add salt, stir again carefully but thoroughly, cover and cook 3 minutes or so, until spinach is cooked down a bit. Serve at once.