Heat the olive oil in a large pot over medium heat. Add the diced onion and cook for 3 minutes until it softens.
Stir in the minced garlic and grated ginger. Cook for 1 minute until fragrant.
Add the curry powder and turmeric. Stir for 30 seconds to toast the spices.
Pour in the rinsed lentils, cubed potatoes, coconut milk, vegetable broth, and salt. Stir everything together.
Bring the mixture to a boil, then reduce the heat to low. Cover and simmer for 25 minutes, stirring once or twice, until the lentils and potatoes are tender.
Ladle the stew into bowls and top with fresh cilantro. Serve with lime wedges on the side.