How to Make It
Preheat broiler to high. Hollow out buns, leaving a 1/2-inch-thick shell. Arrange buns in a single layer on a baking sheet. Broil 1 1/2 minutes on each side or until lightly toasted.
Place 1/4 cup vinegar and sugar in a microwave-safe bowl. Microwave at HIGH for 45 seconds. Stir in red onion. Let stand 15 minutes. Drain.
Combine remaining 1 tablespoon vinegar, 1 tablespoon mayonnaise, yogurt, and dill in a small bowl.
Combine remaining 2 tablespoons mayonnaise, bell pepper, and next 5 ingredients (through yolk). Add panko and crab, stirring to combine. Working with damp hands, divide crab mixture into 8 equal portions, shaping each into a 3/4-inch-thick patty.
Heat a large nonstick skillet over medium-high heat. Add oil to pan; swirl to coat. Add crab cakes to pan; cook 4 minutes on each side or until golden and thoroughly heated.
Spread 1 teaspoon yogurt mixture on bottom half of each bun. Top with 1 patty. Divide onions and arugula among sliders. Top with top halves of buns.