Blackened Tilapia

In a small bowl, combine brown sugar and spices. Rub spice mix all over tilapia.  In a large cast-iron skillet over medium heat, heat oil. Add tilapia and cook until crust is deeply golden and fish flakes easily with a fork, 2 to 3 minutes per side. In a medium bowl, toss avocado, tomato, jalapeño, and cilantro. Add oil and lime juice and season with salt and pepper.  Serve tilapia topped with avocado salsa.