I've modified this to be even quicker.
1 1/2 Tbsp. vegetable oil
1 medium onion, diced
2 tsp. curry powder
1 can coconut milk
1 can diced tomatoes
2 Tbsp. tomato paste (or spaghetti sauce)
1 lb. chicken, cut into 1-inch cubes
1 box frozen spinach, thawed or 3 packed c. fresh baby spinach
1. Heat the oil in a large skillet over medium heat. Add the onion and 1/4 tsp. of salt. Cook the onion, stirring often, until soft (about 5 minutes). Add the curry powder and continue stirring for 1 minute more.
2. Stir in the coconut milk, tomatoes, and tomato paste. Continue cooking the mixture, stirring occasionally, for 5 minutes or until the sauce thickens slightly.
3. Add the chicken, stir well, and cook for 5 to 6 minutes or until the meat is cooked through. Add the spinach and cook, stirring occasionally, until wilted, about 3 minutes. Add more salt to taste. Serve the curry warm over rice.
Makes 6 servings.