Just picked up some lemongrass and I will probably add both chicken and shrimp to this...

SERVES 4 (change servings and units)
Ingredients
1 stalk lemongrass
6 slices gingerroot
1 lime
2 small red chilies
4 cups water
4 tablespoons fish sauce
1 teaspoon chili paste with garlic
6 ounces tomatoes, cut into chunks
4 ounces mushrooms, sliced (I use white or baby bella)
25 small cooked shrimp
2 tablespoons cilantro

Directions
1Cut off the dry end and a few top leaves of the lemongrass stem.
2Bruise the stem with the handle of a knife and cut into 1-inch long pieces.
3Reserve.
4Bruise the chilies, cut them in half, scoop out and discard the seeds.
5Reserve the chilies.
6Bring the water to boil.
7Add lemongrass and ginger, and squeeze out half the lime into the water.
8Boil 2-3 minutes.
9Add fish sauce and chili-garlic paste.
10Cook for another minute.
11Add tomatoes and mushrooms.
12Cook for 2-3 minutes (or longer, until it boils and the tomatoes start to fall apart).
13Squeeze the other half of the lime into the soup.
14Take off the heat.
15Add the chilies and let stand a few seconds, then add the shrimp.
16Garnish with cilantro and serve immediately.
17Leave lemongrass, ginger and chilies in the soup and warn your guests not to eat these.