Add lentils to a small saucepan with 3 cups of water. Cover, bring to a boil, then reduce to medium-low and simmer until tender (25-30 minutes).
2. Saute
Heat oil in a large pot over medium heat. Add onions, carrots, salt and pepper. Cook, stirring occasionally until lightly caramelized (15-20 minutes). Add garlic and coriander. Cook for another minute. Stir in collard greens and cilantro. Cook until collards are wilted (another minute).
3. Simmer
Add 1 cup of water and deglaze the pot. Add lentils with it's water. Add potatoes, lemon juice and remaining 4 cups of water. Bring to a boil over high heat. Reduce to medium-low and simmer, covered, until potatoes are tender (12-14 minutes).
