I adapted this recipe from Nancy McDermott's Real Thai and www.thaitable.com.
3 quarts (12 cups) water plus 1 tbsp. Totole brand chicken base (or use 12 cups unsalted chicken broth)
6 large stalks of lemongrass
6 fresh Kaffir lime leaves (each leaf should have 2 lobes). Can be omitted if you can't find these. I have a Kaffir Lime tree growing in my garden, so there's always a fresh supply. If you love Thai and live in California or Florida, then by all means plant one of these guys - they will even thrive in a container! You can buy plants online at www.fourwindsgrowers.com
1 large jalapeno, sliced (for spicier soup, use 2 serrano chilies or 6 Thai bird chilies instead) - leaving the seed in will make it even spicier!
Juice of 2 limes
6 green onions, cut into 1" sections
1 cup fresh cilantro, chopped
1 tsp. brown sugar
2 tbsp. fish sauce
1 tbsp. roasted chili paste or Tom Yum Soup Paste. Tom Yum paste is generally a blend of oil, garlic, shallots, chili, sugar, salt, lemongrass , galangal (a rhizome that tastes like ginger), and oftentimes MSG - yikes! Available in jars in most Asian markets
15 oz. can whole straw mushrooms, drained
1 lb. medium shrimp, deveined (leave shells on, as they add great flavor to the broth)
1. Bring water & chicken base to a boil in a large stock pan.
2. Prep lemongrass by trimming off the tops, leaving about 6" of the stalk. Remove 1 or two of the tough outer layers, and cut off the root. With the back of a cleaver or chef's knife, bruise the stalk at 1-2" intervals on all sides.
3. Combine fresh chilies with the lime juice, green onions and 3 remaining lime leaves. Set aside.
4. Add lemongrass and 3 of the lime leaves to the broth & reduce to a simmer. Cook about 20-30 minutes or until stock is fragrant and the lemongrass is a dull green color.
5. Discard lemongrass from the broth. Add the roasted chili or Tom Yum paste and straw mushrooms. Bring soup back up to a boil, cook for about 1 minute, then add the fish sauce and shrimp. Cook shrimp for about 1 minute or until it just turns pink. Using a slotted spoon, remove shrimp from the soup to a bowl & set aside (I do this so that the shrimp won't overcook and turn rubbery as the soup continues to cook).
6. Turn off heat and add the chili-lime juice mixture and chopped cilantro to the soup. Adjust seasonings (lime juice, fish sauce, additional chili flakes, as needed).
7. To serve, ladle soup into individual bowls and add a few of the cooked shrimp.