In a small bowl, combine scallions, sesame oil, sesame seeds, ginger, juice from lime, sriracha. Season with salt and pepper to taste; adjust sriracha to taste.
Pat tilapia dry with paper towels and sprinkle fillets with blackened seasoning. Heat a non-stick pan over medium-high heat. Add tilapia fillets and cook until browned and cooked through (about 3-5 minutes per side depending on fillet thickness).
Arrange tilapia on plate and drizzle sauce on top of fillet to taste.
Adjust sriracha to personal spice preference. You can also double the recipe if you would like extra sauce.