Heat a pressure cooker, add onion and garlic and roast for 2 minutes. Drain and add the split red lentils, 2 cups water, black pepper powder, red chilli powder, salt and mix.
Add tomatoes, cover and cook under pressure till 2-3 whistles are given out.Cool and put into a mixer jar and grind till smooth. Pour back into the cooker, add lemon juice and mix and bring it to a boil. Pour into bowls and serve.