Sauté a small onion (sliced thick) in vegetable oil over medium-high heat until golden brown and slightly charred. Add a couple cloves of chopped garlic and cook for a minute. Stir in a tablespoon or so of chat masala and cook for a minute.
Pour in 3 cups broth, making sure to scrape up the brown bits on the bottom of the pan. Stir in 1 cup lentils. Salt to taste. Bring to a boil and then simmer until lentils are soft. Right before serving, stir in a pat of butter. Garnish with chopped cilantro and a lemon wedge.