Wonderfully fragrant lemongrass stalks and lime leaves add plenty of flavour to this soup, but be sure to remove them before serving. Coriander stems with roots attached give a better flavour (wash them well), but lots of coriander is sold without roots - so just add a couple more stems. Bird's-eye chilies are available in many stores, but use 1 or more teaspoons of sambal oelek if unavailable. The dish pairs well with a tofu scramble with some Thai seasonings.
6 cups good-tasting vegetable stock
2 stalks lemongrass, top 4 inches removed
3 whole kaffir lime leaves (available fresh or frozen at Asian food stores)
4 coriander stems with roots attached
1-2 red bird's eye chilies, seeded and sliced
2 teaspoons slivered garlic
1 tablespoon slivered galangal or ginger
1 cup sliced shiitake mushrooms
2 cups soft tofu, diced
2 teaspoons brown sugar
2 to 3 tablespoons fish sauce
2 tablespoons lime juice
6 baby bok choy heads, leaves separated
1/4 cup Thai basil, roughly chopped
1/4 cup fresh coriander/cilantro, roughly chopped
Combine stock, lemongrass, lime leaves, coriander stems, chili chilies, garlic, and galangal or ginger in a soup pot and bring to boil over medium-high heat. Reduce heat to medium and let simmer for 10 minutes or until broth is very fragrant.
Add mushrooms and simmer for 2 to 3 minutes. Stir in tofu, sugar, fish sauce and lime juice, and simmer for 3 minutes or until soup is well flavoured. Adjust seasonings to taste. Add bok choy and simmer 2 minutes or until limp. Add basil and coriander.