Caldo de Camarón (Shrimp Soup)

Ingredients

• 1 lb. unpeeled, medium-size fresh shrimp
• 6 1/2 c. chicken broth
• 3 c. chopped fresh tomatoes
• 4 cloves garlic, peeled and chopped
• 2 serrano chiles, stemmed, seeded, and chopped
• 1 c. chopped white onion
• 1 tsp. dried whole oregano
• 2 T. olive oil
• 2 c. zucchini or crookneck yellow squash, cut into 1/3-inch cubes
• 11/2 c. baking potatoes, peeled and cut into 1/3-inch cubes
• 1/2 tsp. salt, or to taste
• 1/4 tsp. black pepper, or to taste
• Lime wedges
• Warm Mexican rice (optional)