Heat 2 tbsp vegetable oil in large nonstick skillet over medium-high heat. Add sliced onion and a pinch of salt and pepper to one side of skillet. To other side, add burgers. Cook until onions are soft and starting to brown and burgers are golden brown, 5 to 6 minutes per side. Turn off heat, transfer burgers to plate, and cover with foil to keep warm.

Add BBQ sauce to skillet with cooked onions and stir to combine. In small bowl, stir together mayo, garlic, and a pinch of salt and pepper.

Combine arugula, just half the pickled jalapeños, pickling liquid, 2 tsp olive oil, and a pinch of salt and pepper in medium bowl and toss. (TIP: Use more pickled jalapeños if you prefer more spice.)

Place bottom half of each bun on plate. Top with BBQ-glazed onions, black bean burgers, and some spicy arugula salad. Spread aioli on top buns and close burgers. Serve with remaining salad. Dig in!

Wash hands and cutting board well after handling spicy peppers. 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.