Step 1To make the paneer, heat the milk in a heavy pot over medium heat. When it comes to a boil, add the lemon juice and vinegar. Stir until the milk breaks up and curdles. Remove it from the heat and let cool. Strain the curdled milk through cheesecloth and make sure all of the liquid is squeezed out. (Mama's tip was to tie the paneer bundle around the kitchen faucet and let it hang to allow the last drops of liquid to drain into the sink).
Step 2Heat the oil in a wok or a nonstick skillet. Add the onion and cook until light brown. Add the tomato, ginger, coriander, turmeric, red pepper, serrano and salt to taste. Stir until the tomato is tender. Add the crumbled paneer and stir until the cheese is well-coated with the tomato-onion mixture. Cover and simmer over low heat until the flavors have melded, 5 to 6 minutes. Add 1 to 2 tablespoons of water to keep the paneer from sticking to the pan.
Step 3Garnish with the cilantro before serving.