Rinse the lenses cold and let them drip off. Peel and finely chop the ginger. Peel onions and chop finely.
Heat 2 tablespoons of oil in a saucepan. Fry chilli, ginger, cumin, garam masala and mustard seeds briefly while stirring until fragrant. Add the lentils and sauté briefly. Add 1 l water and bring to the boil.
Simmer covered over medium heat for 15-20 minutes, stirring occasionally.
Wash, quarter and dice the tomatoes. Add to the dal about 10 minutes before the end of the cooking time. Clean and wash the cauliflower and cut into florets. Wash coriander, shake dry, pluck leaves from stems and chop finely.
Heat 1 tablespoon of oil in a frying pan. Fry the cauliflower for 5-8 minutes until golden brown. Season with salt and pepper.
Add chopped coriander to the lentils. Season to taste with salt and lemon juice. Serve with roasted cauliflower in four deep plates.