Slice 250g of button mushrooms. Whisk 4 tablespoons of room-temperature plain yogurt until smooth.
Blend 100g of chopped onion, 1 teaspoon of chopped ginger, and 1 teaspoon of chopped garlic into a smooth paste. Separately purée 70g of tomatoes.
Heat 3 tablespoons of oil. Add ½ teaspoon of cumin seeds, 1 Indian bay leaf, 2 green cardamom pods, 3 cloves, and 1 piece of cinnamon, ½in / 1cm long. Fry briefly until fragrant.
Add the onion paste. Cook over low-medium heat, stirring, until golden. Add the tomato purée, ¼ teaspoon of turmeric, ½ teaspoon of red chili powder, and 1 teaspoon of ground coriander. Cook until the oil separates.
Reduce the heat to low. Add the mushrooms and yogurt, stirring quickly. Simmer for 2-3 minutes.
Add ¾ cup of water and salt. Cover and simmer for 18-20 minutes, until the mushrooms are tender.
Remove the whole spices. Stir in ¼ teaspoon of garam masala, ½ teaspoon of crushed dried fenugreek leaves, and 2 tablespoons of chopped cilantro.
