Chicken Saag (chicken and spinach curry)

Name: Chicken Saag (chicken and spinach curry)
Prep time: 10 min
Cook time: 20 min
Total time: 30 min
Cuisine: Asian, Indian
Ingredients: 2 Tbs vegetable oil; 1 large onion, finely chopped; 2 cloves garlic, minced; 2 Tbsp fresh ginger, minced; 1 1/2 tsp salt; 1 1/2 tsp coriander; 1 1/2 tsp garam Masala; 1 tsp ground tumeric; 1 tsp ground cumin; 1/2 tsp ground cardamom; 1/4 tsp Indian chili powder or Cayenne pepper; 1 Tbsp tomato paste; 1/2 c water; 8 oz baby spinach; 1 lb chicken, shredded or cubed; 1/4 c plain Greek yogurt