Rinse the chicken under running water and place it on a plate. Pat dry the chicken with a paper towel before cutting it into 1½ in pieces and then place it in a mixing bowl.
Blend the Serrano peppers, garlic, ginger, and almonds to a paste with a little water.
Add the blended spices along with salt and the turmeric powder to chicken pieces and mix well. Set the chicken aside for at least thirty minutes.
Heat the oil in a heavy bottom pan on medium-high heat. Add the onions to the hot oil and sauté them until they are soft. Add the cumin powder, red chili powder, and coriander powder and continue to sauté for two more minutes. Add the pureed tomatoes and continue to sauté until the spice mixture is soft and releases oil around it. Adjust the heat while sautéing the spices to prevent them from burning.
Add the marinated chicken pieces to the sautéed spices and turn them with the spatula until the pieces are coated with the spices.Adjust the heat and continue to sauté the chicken pieces until the raw fragrance of garlic and ginger goes away. It should take about 5-7 minutes.
Add water to the chicken and stir well. Bring the chicken curry to a boil and let it simmer for eight more minutes.
Add the garam masala to the curry and mix it well. Let the curry simmer for one more minute and turn the heat off.
Garnish with cilantro and serve it hot over steamed rice or naan.