Turkey Mustard Burgers

1 pound ground turkey
1/4 cup minced red onion
1 tablespoon dijon mustard
1 teaspoon coarse salt
1 tablespoon olive oil, or as needed
4 hamburger buns
1 cup baby arugula
1 avocado-peeled, pitted, & sliced
4 slices of green bell pepper
1/2 cup grated parmesan cheese

-Mix the first 4 ingredients together, form into 4 patties, & refrigerate for 30 minutes
-Preheat the grill to medium high heat & lightly oil the grate
-Drizzle olive oil over the burgers. Cook the burgers on the grill until no longer pink in the center & the juices run clear, about 4-5 minutes per side. Internal temperature should be at least 165 degrees F
-Serve on buns topped with arugula, avocado, green bell pepper, & parmesan cheese