Wash the rice and lentils at least three times in fresh water and drain well.
Heat the vegetable oil in a large pan over a medium heat, add the bay leaf and cumin seeds. Cook for 1 min, then add the grated ginger and cook until fragrant. Add the asafoetida, onion and green chilli, then cook until softened (about 5 mins).
Add the tomato, turmeric and a large pinch of salt and cook for 3–4 minutes. Add the drained rice and lentils and give everything a stir. Add 750ml water for a thick consistency, or if you prefer a looser, porridge-like khichadi, add 1 litre of water.
Stir once, check for seasoning, then leave to simmer while you cook the mushrooms. Occasionally stir the mixture – if it begins to stick, add a little more water.
To cook the mushrooms, heat 1 tbsp of the oil in a non-stick frying pan over a medium heat. Add the mushrooms with a large pinch of salt and cook until the mushrooms are golden brown all over and most of the moisture has evaporated.
Meanwhile, place another frying pan over a medium heat with the remaining tablespoon of oil. Add the cumin seeds and once they begin to sputter and crackle, add the onion and cook until caramelised, crisp and golden brown.
Add the ginger-garlic paste to the onions, cook for a few minutes, then add the turmeric, coriander, chilli powder, garam masala and cumin seeds.
Cook gently for 4–5 minutes, then add the chopped tomatoes and simmer until they break down (about 10 minutes). Add the caramelised mushrooms, give everything a good mix and remove from the heat.
By this time the khichadi should be ready – taste a spoonful of the rice and lentils to ensure they’re cooked through. To serve, stir the mushroom mixture into the rice and divide between bowls.
Drizzle with truffle oil, generously cover with shaved or grated truffle and garnish with coriander or pea shoots. Serve with poppadums, chutneys and pickles on the side if desired.