Special equipment: a gas grill and eight 10- to 12-inch metal skewers (or bamboo skewers that have been soaked in water)
Preheat a gas grill to high heat.
For the bourbon teriyaki sauce: Add the soy sauce, bourbon, mirin, sugar, honey, ginger, sesame oil, mustard, sriracha, garlic and lime juice to a medium bowl and whisk to combine. Reserve 1/4 cup of the sauce to drizzle on the finished skewers.
For the skewers: Skewer alternating pieces of shrimp and steak on each skewer until you have 4 pieces of each per skewer. Put the skewers on a baking sheet or in a 9-by-13-inch baking dish. Lightly season with salt and season generously with pepper. Brush the skewers with some of the remaining bourbon teriyaki sauce.
Brush the grill grates with canola oil. Grill the orange wedges until grill-marked and slightly charred, 2 to 3 minutes per side; set aside. Grill the shrimp and steak skewers for about 2 minutes. Flip and brush with more of the remaining bourbon teriyaki sauce and grill another 2 minutes. Turn the heat to medium low and grill the skewers an additional 1 to 2 minutes per side, basting with more sauce.
Transfer the skewers to a platter and garnish with the oranges, scallions and sesame seeds. Drizzle with the reserved bourbon teriyaki sauce.