Step 1

Clean mushrooms with a brush to remove any dirt or debris. If mushrooms are difficult to clean with a brush without bruising, fill a salad spinner with cold water, add mushrooms to basket, and quickly plunge them into the water, agitating to remove dirt. Empty the dirty water, and quickly but gently spin the mushrooms dry. Arrange cleaned mushrooms on a baking sheet lined with paper towels, and season with 1 teaspoon salt and pepper. Refrigerate mushrooms, uncovered, at least 6 hours or up to 2 days.

Step 2

Heat one chimney of charcoal until flames subside and coals are lightly covered in ash. Arrange coals for two-zone cooking: Bank coals along half of bottom grate of charcoal grill. Place applewood log along edge of coals. 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).

Step 3

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.

Step 4

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. Uncover and carefully remove dish to a heatproof surface.

Step 5

Toss greens with lemon juice. Divide crème fraîche among plates, and scatter mushrooms over crème fraîche. Drizzle each plate with 1/4 teaspoon honey, and top loosely with greens. Serve immediately.