1 cup pearl barley
6 cups homemade or low-sodium store-bought chicken stock
2 tablespoons extra-virgin olive oil
1 cup finely chopped onion
1/2 cup dry white wine
12 ounces rock shrimp, peeled Maine shrimp, or other small peeled shrimp
2 1/2 cups frozen peas, thawed
1 tablespoon finely grated lemon zest
2 tablespoons fresh lemon juice
1/4 cup finely grated Parmesan cheese
1 teaspoon coarse salt
Freshly ground pepper