How to Make It
Rub the cut sides of the lobster tails with 1 tablespoon of the olive oil and 1/2 teaspoon of the garlic. Season the lobster with salt and pepper.
In a large steamer, combine 1/2 cup of the wine with the lemon juice, juniper berries, bay leaves and thyme sprigs. Add 2 inches of water, then the lobsters, cut side up, in a steamer basket and cover tightly. Steam the lobsters over high heat about 8 minutes, or until the tails are cooked through and the claws are red.
Meanwhile, in a large skillet, heat the remaining 1/4 cup of oil until shimmering. Add the mushrooms and cook over high heat until tender and just beginning to brown, about 8 minutes. Add the remaining 1 teaspoon of garlic and the chopped thyme and cook until fragrant, about 1 minute. Add the remaining 1/4 cup of white wine and cook until almost evaporated. Season with salt and pepper.
Transfer the lobster to 4 large plates. Spoon the mushrooms onto the sourdough toasts and serve alongside.