Heat 6 tablespoons oil in a large, deep saucepan over medium-low heat.
Add the sliced onion and cook, stirring, until tender.
Add the cinnamon sticks, dal, and ginger. Cook, stirring often, 10 minutes.
Add the stock, 2 cups water, red pepper, and salt to taste. Bring to a boil, reduce heat, and simmer 10 minutes.
Squeeze juice from the lemon halve, straining the seeds. Add the lemon juice and the lemon halve to the lentils. Cook 50 minutes, stirring often. Add up to 1 cup more water, if dal dries out too much.
Heat the olive oil in a small pan. Add chopped onion, garlic, chili and bay leaves. Cook, stirring, until onion is browned. Add mixture to lentils and stir. Serve hot.