Start by making the onion paste by microwaving chopped onions with water and blending them to a smooth consistency.
Onions, Water
In a pot, heat oil and add garlic ginger paste. Cook until fragrant.
Vegetable oil, Garlic ginger paste
Add the spice mix (cumin, coriander, turmeric, chilli powder, kasoor methi, garam masala, salt) and cook until fragrant.
Cumin powder, Coriander powder, Turmeric, Mild Kashmiri chili powder, Dried fenugreek leaves, Kosher salt, Garam masala
Stir in diluted tomato paste and cook for 1 minute.
Tomato paste
Add the onion paste and cook for 3-4 minutes.
Add the chicken and simmer until cooked through.
Boneless chicken thighs
Stir in thawed spinach and simmer for another minute.
Frozen spinach
Taste for seasoning and adjust as needed.