Add 2 cloves of garlic, the fresh ginger, the ground turmeric, the ground cumin, the ground coriander, the ground fenugreek, the mustard powder, 2 tablespoons of groundnut oil, the tomato purée, 1 green chili, the salt, 1 tablespoon of water, and 10 stalks of fresh cilantro to a food processor and blend until a smooth has formed, to make the jalfrezi curry paste.
In a large, deep pan, add the sliced onion and peppers with the remaining tablespoon of groundnut oil. Fry the vegetables on medium high heat for a minute or two. Then add the remaining garlic clove, along with 2 green chillies, and fry everything for another minute or two.
Reduce the temperature to a medium heat, then add the jalfrezi curry paste to the pan and fry for a few minutes until it is fragrant.
Add the can of tomatoes to the pan, along with the coconut milk. Stir everything together and then allow it to gently simmer for 5 to 10 minutes until the sauce has reduced and thickened.
Add the raw shrimp and the lemon zest to the pan and cook for 6 to 8 minutes until the shrimp are just cooked through.
Serve hot with rice and a sprinkling of chopped cilantro.