1/3 cup plain nonfat yogurt
1 tablespoon tandoori masala powder
1 1/2 pounds boneless, skinless chicken thighs, cut into 1-inch pieces
1/2 onion, chopped
1 (1 inch) piece fresh ginger
1 clove garlic
2 tablespoons water
3 tablespoons cooking oil, divided
2 teaspoons garam masala
1/4 teaspoon Indian chili powder
1 cup tomato sauce
1 cup half and half
2 tablespoons butter
1 teaspoon dried fenugreek leaves
1 teaspoon salt