In a large pot, heat the olive oil over medium heat. Add the diced onion and sauté for 3-4 minutes until translucent.
Stir in the minced garlic and grated ginger, cooking for an additional 1-2 minutes until fragrant.
Add the red curry paste, turmeric powder, and cumin powder to the pot, stirring well to coat the onion mixture. Cook for another minute.
Pour in the vegetable broth and coconut milk, stirring to combine.
Add the rinsed lentils, diced carrots, and bell pepper to the pot. Bring the mixture to a boil, then reduce the heat to low and cover. Simmer for 25-30 minutes or until the lentils and vegetables are tender.
Once cooked, stir in the chopped spinach leaves and cook for an additional 2-3 minutes until wilted.
Season with salt and pepper to taste.
Serve the soup hot, garnished with fresh cilantro and lime wedges on the side.