1. Heat the oil; add cumin seeds and onions and fry till the cumin changes color.
2. Add the turmeric powder and yellow split peas; fry 1 minute.
3. Add the water, salt, cayenne and black pepper; bring to a boil and simmer for 30 minutes or until the yellow split peas are tender & strain them.
4. Add lemon juice to the strained fluid. Use the strained lentils for another dish or discard them.