Poached Cod with Tomatoes

Name: Poached Cod with Tomatoes
Ingredients: 3 cups low-sodium chicken broth; 1/2 medium red onion, very thinly sliced; 2 cups cherry tomatoes, cut in half lengthwise; 1/2 pound small potatoes, preferably fingerling and purple, sliced into ¼-inch rounds; 3 sprigs basil, plus leaves for garnish; 1/4 teaspoon red-pepper flakes; Coarse salt and freshly ground pepper; 4 skinless cod fillets (4 ounces each); 4 ounces snap peas, trimmed and thinly sliced on the bias; 1 teaspoon fresh lemon juice, plus 4 lemon wedges, for serving; Extra-virgin olive oil, for drizzling