"This is a refreshing, light dish that can be used as a main protein for a summer meal or as an appetizer for a dinner with guests. If you have trouble finding langostinos you can always substitute shrimp. This is a gluten-free and dairy-free dish, so can be good when you are dealing with potential food allergies."
Combine langostinos, red bell pepper, rosemary, sea salt, red pepper flakes, white wine, and balsamic vinegar, in respective order, in a large bowl. Toss until langostinos are evenly coated. Cover bowl with plastic wrap and refrigerate until flavors blend, 4 hours to overnight.