Potato and Cauliflower Curry

1 jalapeno pepper, minced
1/2 " section ginger root, peeled and minced
1 teaspoon cumin
1/2 teaspoon mustard seeds
2 Tablespoons oil
2 Tablespoons butter
3 medium potatoes, cut in 1/2 " chunks
2 lbs. cauliflower, cut in bite-sized pieces
1/2 lb. chopped tomatoes (or 1 cup tomato puree plus 1/2 cup water)
1/2 teaspoon turmeric
2 teaspoons ground coriander (or substitute fresh cilantro and add it when you add the parsley)
1 teaspoon salt
1/4 cup chopped fresh parsley

Heat oil and butter in a heavy kettle.  Add the jalapeno, ginger, cumin, and mustard seeds, and cook until the seeds sputter and pop.  Add potatoes and cauliflower and cook 4-5 minutes or until lightly browned.  Add the tomatoes, turmeric, coriander, salt, and half the parsley and stir well.  Cook gently over low heat, stirring occasionally, until the vegetables are as tender as you like them.  Add the remaining parsley and serve with baked squash, and a salad of endive, arugula, and sliced apple.
Serves 2-3.