Place a large pot over medium heat, add in your broth and water and bring to a boil. Once it is boiling, bring heat down to a simmer, add the garlic, chili peppers and lemongrass.
Continue to simmer and add in tomatoes, onion, mushrooms and lime juice. Cook until the vegetables start to become soft (about 5 to 7 minutes) and add the shrimp.
Cook the shrimp for 6 to 8 minutes or until cooked through, stirring occasionally. Stir in the fish sauce and sugar. If desired, stir in the coconut milk and sambal. If desired, serve topped with the cilantro and serve the lime wedges on the side.
This nutritional information refers to each serving of the entire recipe and not just the products used as ingredients.