It has insulated walls with enough space to hold up to 18 cans or 28 pounds of ice.
Place cooking grate over coals; open bottom and top vents of grill.Close grill lid, and heat to medium-high (400°F to 450°F).. Blot any moisture from surface of mushrooms, and transfer to a large bowl.
Toss with oil, and arrange in a single layer on oiled grates over direct heat.Grill, uncovered, turning occasionally, until mushrooms are tender, deeply caramelized on the surface, and crispy in some areas, 10 to 12 minutes.As mushrooms finish cooking, transfer to grate over indirect heat.
When all mushrooms are cooked, transfer to a bowl.Season with remaining 1 teaspoon salt, and cover loosely with aluminum foil to keep warm.. Place crème fraîche in a shallow 6-inch-wide heatproof metal pan or ceramic dish, such as a small cake pan or crème brûlée dish, and place on cool side of grill.
Working quickly, add juniper berries (or branch, if using) to hot coals, and cover grill with open lid vents over crème fraîche.
Smoke crème fraîche until melted and light brown on surface, about 5 minutes.Cover and braise in the oven for 45 minutes, until the vegetables are tender..
Transfer the roast to a work surface.Using a slotted spoon, transfer the vegetables to a deep serving platter; cover.
Boil the liquid until reduced to 3 1/2 cups.Stir the cornstarch slurry and whisk it into the simmering liquid until thickened..