1. Heat grill to medium-high. Cut a deep slit shrimp, through shell, down ridged back and remove vein. Rinse and pat shrimp dry. Whisk thyme leaves, lime juice, 1 tablespoon of olive oil, 1/2 teaspoon of salt, and black pepper to taste in a shallow glass dish. Add shrimp and refrigerate for 30 minutes.
2. Pulse garlic, jalapeno, scallions, remaining 1 tablespoon olive oil, and remaining 1/2 teaspoon salt in a food processor to a coarse paste. Add cilantro and pulse to incorporate. Spoon mixture into slit in shrimp and press to close opening. Lay shrimp on grill and cook for 3 minutes. Turn over, cover, and grill until shrimp turn pink and are slightly firm to touch, about 2 more minutes. Sprinkle with salt and serve.
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