2 cups low-sodium or homemade chicken stock, or vegetable stock
1/2 lb medium shrimp, shells removed and reserved
2 Thai bird chiles, seeds removed, sliced (use more, or less, to taste; for fiery hot soup, leave the seeds in)
1-inch piece of lemongrass
2 fresh kaffir lime leaves, or 1/2 tsp grated lime zest
1 cup canned straw mushrooms, sliced in half lengthwise
3 Tbsp fresh lime juice (from 2 limes)
3 Tbsp fish sauce
In a sauce pan, simmer the stock and reserved shrimp shells for 20 minutes. Strain, and return the stock to the pan. Add chiles, lemongrass and lime leaves, reduce heat to simmer, and cook for 5 minutes. Remove lemongrass and lime leaves, and add the shrimp and mushrooms. Cook for 2-3 minutes, until shrimp are done but not overcooked. Stir in the lime juice and fish sauce, cook for 1 minute until flavors combine, and serve hot.