A mozzarella-topped burger turns decadent when you start with an 80/20 chuck blend for juiciness, mix MEATBALL15 into the patty for herb-garlic depth, and crown it with oven-baked onion petals tossed in FJORD FIRE for smoky heat. 

The patties grill (or skillet-sear) in eight minutes, the onions roast alongside, and everything lands on a toasted brioche for a bold but balanced bite. 

• Pre-heat oven to 220 °C / 425 °F .

• Toss onion petals with OLEA432, FJORD FIRE, and salt; spread on a parchment-lined sheet.

• Roast 15 min, stirring halfway, until edges char and centers turn sweet-soft

In a cold bowl combine beef and MEATBALL15; mix gently just until spices are streaked throughout (over-mixing = dense burgers

Divide into 4 equal balls (≈170 g). Press into 1.5 cm-thick patties, slightly wider than buns; make a thumb dimple in the center to prevent dome rise.

Grill or cast-iron skillet, medium-high heat.

1. Season exteriors with salt & pepper.

2. Cook 3–4 min per side. Add mozzarella for last 1 min; cover to melt.

3. Check internal temp hits 71 °C / 160 °F (USDA ground-beef safety

Toast buns cut-side down 1 min. Layer arugula, patty, a scoop of spicy onions, tomato, and top bun.

• Choose 80/20 ground chuck (or chuck + brisket) 
  for the ideal fat-to-lean ratio—juicy without excessive shrinkage. 

• Keep the meat cold 
  from grinder to grill; chilled fat shears cleanly and stays in the patty for better moisture. 

• Handle the beef as little as possible 
  Mix just until the spices streak through; over-working binds proteins and makes burgers dense. 

• Season exteriors with salt and pepper right before cooking 
  salting earlier turns ground beef sausage-like and tight. 

• Form 1.5 cm-thick patties with a thumbprint dimple in the center to prevent doming as they cook. 

• Cook over medium-high heat 3-4 min per side (grill or cast iron) for a browned crust; add cheese during the last minute and cover to melt. 

• Use an instant-read thermometer and pull patties at 71 °C / 160 °F —the USDA’s safe temperature for ground beef. 

• Serve burgers hot; don’t rest them like steaks —resting can let melted cheese cool and fats congeal, according to grill cooks’ tests. 

• Toast brioche or potato buns briefly to add crunch and protect against juice soak-through (common in burger competitions). 

• Use a light oil or beef tallow wipe on grates/skillet to prevent sticking; avoid pressing the patty while it cooks—pressing squeezes out juices.