- Preheat grill to medium-high. Season burgers with salt and pepper.
- Grill onion over direct heat, flipping occasionally until onions have become slightly translucent and taken on dark grill marks; remove from heat.
- Grill burgers 4-5 minutes, flip and add brie cheese to each patty. Sear burgers 3-4 more minutes or until the internal temperature reaches 160 degrees and cheese has melted.
- Build burgers with fig spread on the bottom bun followed by burger and Brie, grilled onions, arugula, and finish with toasted bun top.