Combine ½ cup lemonade and ¼ teaspoon coriander for marinade. Add shrimp and marinate for a minimum of 30 minutes.
Prepare vinaigrette by placing ½ cup lemonade, shallot, and remaining coriander in a saucepan over medium-high heat. Reduce to ¼ cup, about 15 minutes. Cool. Whisk 1½ tablespoons of olive oil into the lemonade reduction and season with salt. Chill.
Remove shrimp from marinade and drain. Discard marinade. Season shrimp with salt and black pepper. Dredge in flour and shake off excess. Dip in egg white and drain excess. Press shrimp into coconut to coat on all sides.
Heat remaining olive oil in a non-stick skillet over medium heat. Add shrimp and sauté on first side until golden brown, about 3-5 minutes. Carefully turn shrimp over and sauté until shrimp are cooked through, about 3-5 minutes. Hold warm.
Add parsley to vinaigrette and whisk to blend. Place a small bed of four romaine leaves on each serving plate. Top with lemon slices and star fruit, if using. Drizzle with vinaigrette. Add shrimp and serve.