Preheat oven to 425°F. Combine Brussels sprouts, 2 tsp vegetable oil, and a pinch of salt and pepper on one half of baking sheet and toss to coat. On other half of baking sheet, combine sweet potato, 2 tsp vegetable oil, ¼ tsp pepper, and a pinch of salt and toss to coat. Roast until sprouts are browned and crispy and potato is soft, 18 to 22 minutes.

Meanwhile, combine coleslaw, cranberry sauce, orange zest, orange juice, just half the vinegar, and a pinch of salt and pepper in medium bowl. Set aside slaw. Transfer roasted potatoes to separate medium bowl, add minced sage and ¼ tsp salt, and mash using back of fork until mostly smooth. Set aside.

Heat 1 tbsp vegetable oil in small saucepan over medium-high heat. Add whole sage leaves and fry until crispy, about 1 minute. Using slotted spoon, transfer fried leaves to cutting board, leaving sage oil in saucepan. Chop fried sage, transfer to small bowl, and stir in mayo and remaining vinegar. Set aside.

Heat sage oil in same saucepan over medium heat. Add garlic and just half the flour and cook until softened and beginning to brown, 2 to 3 minutes. Whisk in broth concentrate and ¾ cup water. Bring to a boil and cook until thickened, 5 to 7 minutes. Season to taste with salt and pepper.

Spread mashed sweet potatoes on bottom halves of toasted buns. Top with roasted Brussels sprouts and cranberry slaw. Spread sage mayo on top halves of buns and close sandwiches. Serve with remaining slaw and gravy for dipping. Dig in!

For 4-serving meal, double all ingredients. You may need to cook in batches, in larger cooking vessels, or for longer cook times. Follow visual cues in 2-serving recipe.