Preheat oven to 375° F.
Peel the sweet potatoes, then cut into cubes. Add to a baking sheet, drizzle with 2 tablespoons olive oil. Roast until the potatoes are fork tender, about 20 minutes (boiling the potatoes will add too much moisture to the filling).
Add the potato chips and the oats to a food processor, process until just crumbs remain.
In a large mixing bowl add the chip crumbs, sweet potato cubes, cooked quinoa, black beans, cilantro, onions, garlic powder, smoked paprika, and beer. Mix until well combined. Form into 6 large patties, about ¾ inch tall.
Heat remaining olive oil in a skillet over medium high heat, cook the patties until golden brown on each side, adding more olive oil to the pan when it starts to dry.
In a small bowl stir together the sauce ingredients.
Plate burgers in the buns topped with avocado slices, tomato, sauce and potato chips (if using), serve immediately.
To make in advance, make the burger patty mixture, add to an air tight container, chill for up to three days before using.