Ingredients

• 1 shallot, finely chopped
• 2 sprigs tarragon, plus 2 teaspoons chopped
• 1/2 teaspoon black peppercorns, crushed
• 1 tablespoon white wine vinegar
• 1 cup plain whole-fat Greek yogurt
• 2 tablespoons fresh lemon juice
• 1 tablespoon olive oil
• Kosher salt
• 1 tablespoon coriander seeds
• 1 teaspoon kosher salt
• 1 teaspoon mustard powder
• 1 teaspoon paprika
• 12 ounces maitake or oyster mushrooms, torn into large pieces
• 2 tablespoons olive oil
• Torn tarragon sprigs (for serving)
• A spice mill or a mortar and pestle

Instructions

1. Bring shallot, tarragon sprigs, peppercorns, vinegar, and 1/3 cup water to a boil in a small skillet over medium heat and cook until liquid is nearly evaporated, 8–10 minutes. Let cool. Discard tarragon sprigs and transfer mixture to a small bowl. Add yogurt, lemon juice, oil, and chopped tarragon and mix well; season with salt.
2. Prepare a grill for medium heat. Finely grind coriander seeds in spice grinder or with mortar and pestle. Transfer to a small bowl and mix in salt, mustard powder, and paprika.
3. Drizzle mushrooms with oil in a medium bowl; gently toss to coat. Season with rub. Grill, turning occasionally, until browned and tender, 6–8 minutes. Serve over yogurt topped with tarragon.
4. Yogurt can be made 3 days ahead. Cover and chill.