In a Saucepan or Dutch oven, warm up the coconut oil on medium heat. Add onion, ginger, garlic and lemongrass stalks. Sauté for 3 minutes till onions get browned.
Add water or vegetable broth and let it come to a boil. Simmer it for 3 minutes until the flavors are extracted in the broth. Turn off the heat. Using the slotted spoon or a strainer, remove the onion, ginger, garlic and lemongrass stalks and discard them.
Put the broth back on the stove on medium heat. Add tofu cubes, mushrooms and bell peppers. Stir well. Cover the pot with lid and let them cook for 5 minutes until mushrooms are tender.
Add coconut milk, Thai Chili paste, soy sauce and sweetener. Mix well. Let the soup come to a gentle boil. Turn off the heat. Add in lime juice. Adjust the seasoning, salt and pepper. Delicious vegan tom kha with tofu and vegetables is ready !
Ladle the soup in the bowl. Garnish with lime wedges, green onions, and cilantro. Serve warm and enjoy !