Rinse the red lentils under cold water and set them aside. Heat the vegetable oil in a large pot over medium heat.
Add the diced onion, minced garlic, and minced ginger to the pot. Cook for 3 to 4 minutes until the onion softens.
Stir in the bruised lemongrass stalks, chopped bell peppers, and Thai red curry paste. Cook for another 2 minutes to release the aromas.
Add the rinsed lentils and vegetable broth. Bring the mixture to a gentle boil, then reduce the heat and simmer uncovered for 20 minutes until the lentils are tender.
Pour in the coconut milk and add the salt. Stir well and simmer for 5 more minutes. Remove the lemongrass stalks before serving.
Ladle the stew into bowls and top with fresh cilantro and a squeeze of lime.