Cut 500g of boneless chicken into 1in / 2.5cm cubes. Mix with 1 tablespoon of lemon juice, ¼ teaspoon of ground black pepper, ¼ teaspoon of Kashmiri chili powder, and ¼ teaspoon of salt. Cover and set aside.
In a pan, heat a little of 2 tablespoons of oil, about 1 teaspoon. Stir-fry 16 cashews and 2 green chilies briefly, add 250g of baby spinach, and cook for about 6 minutes, until wilted.
Cool, then blend with ½ cup of cold water to a smooth purée.
Heat the remaining oil in a pot. Fry ¾ cup of finely chopped onion until soft and light brown. Stir in 2 teaspoons of ginger-garlic paste, then add ¾ cup of chopped tomato and ¾ teaspoon of salt, and cook until mushy.
Add the chicken and stir-fry until it turns pale. Stir in ½ teaspoon of garam masala and ½ cup of hot water, cover, and cook over medium heat until the chicken reaches 165°F / 74°C.
Stir in the spinach purée and simmer for 3-4 minutes. Adjust the salt and crush in 1 tablespoon of kasuri methi (dried fenugreek leaves).
