How to Make It
In a large bowl, toss the shrimp with the lime juice and 1/4 cup of the olive oil. Cover and refrigerate for 1 hour.
Meanwhile, in a small skillet, toast the caraway, coriander and cumin seeds over moderate heat until fragrant, about 2 to 4 minutes. Transfer to a spice grinder and let cool, then add the crushed red pepper and grind into a powder. In a large bowl, whisk the ground spices with the remaining 1/4 cup of olive oil, the paprika, garlic and 1/4 cup of water. Season the harissa with salt.
Light a grill. Season the shrimp lightly with salt and grill over high heat, turning, until lightly charred and just cooked through, about 4 minutes. Add the shrimp to the harissa and toss to coat. Transfer the shrimp to a platter and serve with lime wedges.