Asian Chicken Stock:

• 1 (4-pound) free-range chicken
• Reserved shells from shrimp, see below
• 6 scallions
• 4 cloves garlic
• 1 stalk lemongrass, lightly smashed, or zest of 1 lemon
• 1 tablespoon whole black peppercorns
• 1 (2-inch) piece fresh ginger, sliced thick
• 4 kaffir lime leaves, fresh or frozen, or juice and skin of 1 lime
• 2 serrano chiles, halved lengthwise

Soup:

• 1 recipe Asian Chicken Stock
• 1 (15-ounce) can straw mushrooms, drained and rinsed
• 2 limes, juice and skins
• 4 serrano chiles, halved lengthwise
• 1 teaspoon fish sauce, or more to taste
• 5 kaffir lime leaves, fresh or frozen, optional
• Kosher salt
• 1 pound large shrimp, shelled and sliced in 1/2 lengthwise
• 2 tablespoons chopped fresh cilantro leaves, plus more for garnish
• 1 tablespoon Thai basil leaves or regular basil leaves