Begin by parboiling 650 g baby potatoes in salted boiling water for just under 5 minutes. Drain, cool, and then peel the potatoes.
Heat 1 litre oil in a large deep-fat fryer or kadai*. Use a food thermometer and add the potatoes once the oil reaches 190℃ (375 degrees℉). Fry until golden brown, then drain on kitchen paper and set aside.
Heat 1 ½ tablespoons mustard oil in a large kadai over low-medium heat and immediately add 1 teaspoon cumin seeds. Once they gently crackle, add 3 pods green cardamom, 1 pod black cardamom, 1 stick true cinnamon, 3 leaves Indian bay, and 2 cloves.
Add 1 red onion and sauté until golden to develop the depth of flavour. Add 2 teaspoon ginger garlic paste, stir until the raw smell fades, then add 240 g tomato, which has been made into a paste. Mix well.
Add the ground spices, including ¼ teaspoon turmeric powder, 1 teaspoon coriander powder, ½ teaspoon red chilli powder, and 2 teaspoon Kashmiri chilli powder. Mix well and let the base cook over low heat for at least 10 minutes, stirring consistently to avoid sticking. Add a dash of hot water if necessary.
Add 300 ml water to adjust the consistency. Next, take 180 g yoghurt in a bowl and whisk it thoroughly. Add the yoghurt to the curry gravy along with the fried potatoes, and stir well. Let it simmer until the potatoes have softened (test with a knife).
Season the curry with 1 teaspoon dried fenugreek leaves (crush this between your palms before adding to bring out the aroma), ⅛ teaspoon garam masala, Sea salt to taste, and 1 tablespoon double cream. Mix, turn off the heat, and serve with fresh coriander.
Notes
* Always exercise caution when cooking with large amounts of hot oil. If you prefer, you can air-fry the potatoes.