Is this curry very spicy?
It can be. As written, it is medium. For mild, skip the serrano and use only 1/4 teaspoon Kashmiri chili powder (or paprika). For spicy, add an extra serrano or 1/2 teaspoon cayenne.
What is Kashmiri chili powder and what can I use instead?
Kashmiri chili powder is known for deep red color and gentle heat. Swap in sweet paprika for color plus a pinch of cayenne for heat, to taste.
Can I make it vegetarian or vegan?
Yes. Use chickpeas or roasted cauliflower and use coconut milk instead of cream. Also swap the ghee or butter for more oil (or a plant-based butter) and skip the yogurt and raita, or use a dairy-free yogurt. Most garam masala blends are vegan, but check the label if you are strict about it.
Why did my spices taste bitter?
Most likely they burned. Ground spices only need 10 to 30 seconds in hot oil, or just until fragrant, before you add tomato. If the pot is very hot, pull it off the heat when you add them, then stir like your life depends on it.
How do I thicken a curry that is too thin?
Simmer uncovered until it reduces. If you want a faster fix, mash a few spoonfuls of chickpeas in the pot. You can also finish with yogurt, but do it gently: temper 1 to 2 tablespoons of plain yogurt with a spoonful of warm curry, then stir it in off-heat or over very low heat so it does not split.
Can I use chicken breast?
You can, but thighs stay juicier. If using breast, keep the simmer gentle and stop cooking as soon as it is done so it does not dry out.
What does “heirloom” mean here?
It is my word for the technique, not a traditional dish name. This is a North Indian-inspired onion-tomato masala style curry, made the home way: layers of flavor, patient onions, and spices bloomed in fat.