Before starting, preheat the broiler to high. Wash and dry all produce. Peel, then cut onion into 1/4-inch slices. Heat a large non-stick pan over medium heat. When hot, add 1 tbsp oil (dbl for 4 ppl), then onions. Cook, stirring occasionally, until slightly softened, 3-4 min. Add half the fig spread and season with salt. Cook, stirring occasionally, until onions are dark golden-brown, 5-8 min. Remove the pan from heat, then transfer onions to a plate. Carefully rinse and wipe the pan clean.

Meanwhile, core, then cut apple into 1/4-inch matchsticks. Cut brie in half, through the centre, parallel to the cutting board. Halve buns. Whisk together vinegar, remaining fig spread and 1 tbsp oil (dbl for 4 ppl) in a large bowl. Add apples, then toss to coat.

Arrange buns on an unlined baking sheet, cut-side up. Spread mustard on bottom buns, then top with brie halves, cut-side up. Spread onion mixture on top buns. Broil in the middle of the oven until brie is warmed through, 2-4 min. (TIP: Keep an eye on buns so they don't burn!)

Add arugula and spinach mix to the bowl with apples and dressing. Season with salt and pepper, then toss to combine.

Sandwich top and bottom buns together, then cut sandwiches in half. Divide sandwiches and salad between plates.