Stock for Soup:
Use all shrimp shells, discarded lemongrass stalks, galangal peelings a few black peppercorns, any shallots peelings and place in a pot with 4 cups cold water.
Bring to a boil lower heat to simmer about 30-40 minutes and strain.
In a pot put 2 cups stock bring to a boil.
Add tom yum paste, lemongrass, kaffir lime leaves, galangal, shallots, cilantro roots and chilies (if adding).
Boil 2 minutes until fragrant.
Add mushrooms and tomatoes cook until tender 1-2 minutes.
Add shrimp and cook until fully cooked about 2-3 minutes.
Add fish sauce, scallions and cilantro leaves cook briefly.
Add lime juice.
Garnish with Thai herbs (cilantro, Thai, basil, mint) Fresh bean sprouts and coconut milk (if using)