01 - In a medium bowl, combine the parsley, cilantro, garlic, shallot, red wine vinegar, olive oil, oregano, red pepper flakes, sea salt, black pepper, and lemon juice. Stir thoroughly until all ingredients are evenly incorporated.
02 - Set aside 1/3 cup of the chimichurri for finishing. Pour the remaining sauce over the peeled and deveined shrimp in a large bowl or zip-top bag, tossing to coat each piece evenly. Let marinate at room temperature for 15 minutes.
03 - Preheat an outdoor grill or grill pan to medium-high heat, ensuring the grates are clean and lightly oiled to prevent sticking.
04 - Thread the marinated shrimp onto skewers, piercing through both the tail and head ends to keep them flat. If using wooden skewers, soak them in water for at least 30 minutes beforehand to prevent burning.
05 - Place the skewered shrimp on the hot grill and cook for 2 to 3 minutes per side, turning once, until the shrimp turn opaque pink and develop light char marks.
06 - Transfer the grilled shrimp to a serving platter and drizzle generously with the reserved chimichurri sauce. Serve immediately while hot.