Vietnamese Sweet-Sour Shrimp Soup

INGREDIENTS

• 2 tablespoons tamarind pulp (optional)
• 1/4 cup thinly sliced shallots
• 1 tablespoon salad oil
• 1/2 teaspoon minced garlic
• 1/2 teaspoon Asian chili paste or hot chili flakes
• 5 cups fat-skimmed chicken broth
• 1 pound (30 to 35 per lb.) shrimp, peeled, deveined, and rinsed
• 1 cup pineapple chunks (3/4 in.)
• 2 tablespoons Asian fish sauce (nuoc mam or nam pla) or reduced-sodium soy sauce
• 3 tablespoons sugar
• 1/4 cup lime juice (6 tablespoons if you don't use tamarind pulp)
• 2 Roma tomatoes (6 oz. total), rinsed, cored, and cut into 1/2-inch wedges
• 2 cups (6 oz.) bean sprouts, rinsed and drained
• 2 tablespoons chopped fresh Thai or anise basil (rau hung que) or regular basil leaves
• 2 tablespoons chopped rice-paddy herb (ngo om) or fresh cilantro
• 2 teaspoons finely chopped fresh Thai (hang prik) or serrano chilies