Combine the crème fraîche and truffle zest and a pinch of salt. Mix well and put in fridge, covered.

Divide the meat into three equal parts and shape into burgers. Press an indentation into the middle to keep the meat from shrinking, and set aside (at room temperature).

Sauté the mushrooms in the truffle oil over medium heat until just cooked. Season with salt and pepper and remove from he

Cook the burgers as desired, on a bbq grill or inside grill.

While the burgers are cooking, lightly brush the ciabatta rolls with some truffle oil. Place cut side down on the grill to heat.

When burgers are ready, assemble the sandwich. Spread some truffle crème fraîche on the bottom bun. Place the burger on top, then top with slices of brie.

Next, top with some sauteèd mushrooms, then add the arugula.

Finally, top with the second half of the ciabatta roll and use a long sandwich pick to secure.