Cookwith - Artisan Brioche Burger with Cheddar & Pickled Onions

Ingredients

• 1 1/2 lbs ground chuck (80/20 beef)
• 1 1/2 tsp kosher salt
• 1/2 tsp freshly ground black pepper
• 4 brioche burger buns
• 2 tbsp unsalted butter, softened
• 4 thick slices aged cheddar cheese
• 1 large heirloom tomato, sliced
• 1 cup baby arugula or spring mix
• 1 small red onion, thinly sliced
• 4 tbsp homemade burger sauce (see step 2)
• Homemade Pickled Red Onions (see step 1)
• Olive oil, for brushing