Make the keema (see link below). You can do this the day before if you want to.
Cook the peas. If they are frozen microwave until warm. If they are fresh shelled peas, drop them into boiling salted water and cook until they turn bright green (probably a couple minutes if they are fresh). Check one. If you like them more done keep cooking until you get what you like.
In a small bowl, combine the cumin, coriander, turmeric, Kashmiri chili powder, kasoor methi and salt. This is your spice mix.
Heat 4 tbsp vegetable oil in a pot over medium heat until it shimmers.
Add the garlic ginger paste. Cook, stirring, until the garlic ginger paste stops spluttering. You'll see what I mean when you do it.
Turn the heat to medium low. Add the spice mix. Stir continuously until it starts to smell really good (about 30 seconds). This is called blooming the spices. It's a key Indian cooking technique. Watch it carefully. If it looks like it's sticking or burning lift the pan from the heat. If the spices burn you need to start over. No way around that.
Add the diluted tomato paste and stir to combine. Turn the heat up to medium. Cook for 1 minute.
Add half the onion paste and turn the heat up to medium high. Stir to combine. Cook for about a minute. Add the rest of the onion paste and stir again. Cook, stirring occasionally for about 4 minutes. Don't worry if it looks dry. You can add a bit of water at the end.
Turn the heat down to medium low. Stir in the tamarind paste. Cover and simmer for another 5 minutes. Add the pre-cooked keema. Simmer to heat the keema through. Add the peas. When the peas are warmed through you are good to go.
If the curry is a bit thick add a bit of water or chicken stock and stir. Taste for salt and adjust as needed.
Garnish with a of cilantro if desired.