Serves 42 tablespoons vegetable oil1 large onion, finely chopped (about 1 cup)2 cloves garlic, minced (about 1 tablespoon)2 tablespoons minced fresh ginger1 1/2 teaspoons salt, plus more as needed1 1/2 teaspoons ground coriander1 1/2 teaspoons garam masala1 teaspoon ground turmeric1 teaspoon ground cumin1/2 teaspoon ground cardamom1/4 teaspoon Indian chili powder or cayenne pepper, or to taste1 tablespoon tomato paste1/2 cup water8 ounces baby spinach (or trimmed regular spinach, washed and dried)1 pound chicken breast or tenders, cut into 1-inch pieces1/4 cup plain yogurt, preferably thick Greek-style
Over medium heat, add the salt, coriander, garam masala, turmeric, cumin, cardamom, and chili powder, and stir on medium-low heat until fragrant, about 30 seconds or so.
Add the tomato paste and water, and stir gently to dissolve the tomato paste and all the spices into the water, creating a thick spiced sauce.
Meanwhile, wipe the skillet clean with a paper towel, return it to medium-high heat, and add another tablespoon of oil.