Sichuan Peppercorn Steak with Grilled Green Onions

Sichuan Peppercorn Spice Mix 3 tablespoons black peppercorns 3 tablespoons Sichuan peppercorns 2 tablespoons dried papaya seeds, optional Sichuan Peppercorn Crusted Steak 4 (8-ounce) beef strip loins, at room temperature 1 tablespoon vegetable oil Kosher salt Grilled Green Onions 2 bunches green onions, roots removed 1 tablespoon vegetable oil, plus more for greasing the grill grate Kosher salt and freshly ground black pepper