Rinse 12 oz. large prawns, peeled, deveined, tails left on, then pat dry thoroughly. Add to a large bowl.

Combine 2 garlic cloves, finely grated, one 2” piece ginger, peeled, finely grated, 1 green Thai or other hot chile, finely chopped, 2 Tbsp. extra-virgin olive oil, and ¼ tsp. Diamond Crystal kosher salt in a small bowl. (Alternatively, pound aromatics whole in a mortar and pestle until a paste forms.) Add half of garlic mixture to prawns and let sit at room temperature for 15 minutes.

Add remaining 1 Tbsp. extra-virgin olive oil to a nonstick skillet over medium-high. When it begins to shimmer, add prawns and cook in 1 layer, undisturbed, until mostly cooked and just starting to curl, about 3 minutes. Flip and continue to cook until fully opaque, C-shaped, and cooked throughout, about 2 minutes. Transfer to a serving platter.

Add 1 tsp. yellow mustard seeds and reserved garlic mixture and cook until mustard seeds begin to pop and garlic mixture is golden, about 2 minutes. Add 2 cups fresh corn (from 3–5 ears) and cook until brightened in color and just cooked through, about another 2 minutes. Season with remaining ¼ tsp. Diamond Crystal kosher salt and scatter over prawns.

Juice ½ lime over prawns and cut remaining ½ lime into wedges. For serving, top with torn cilantro leaves (about ½ cup loosely packed or to taste), freshly ground black pepper, and lime wedges.