Ingredients
1 cup walnut halves, plus 16 more for garnish
1/4 cup chopped parsley
1 clove garlic, peeled
1/2 cup cooked brown lentils
4 tsp. balsamic vinegar, divided
1 tsp. dried rubbed sage
1 tsp. toasted walnut oil
16 large button mushrooms (2-inch diameter), stems removed
1 Tbs. olive oil
1/2 cup low-sodium vegetable broth
Preparation
Purée 1 cup walnuts with parsley and garlic in food processor until thick and pasty. Add lentils, 2 tsp. vinegar, sage, and walnut oil; purée until smooth. Season with salt and pepper, if desired.
Fill each mushroom cap with 11/2 Tbs. walnut mixture, and press remaining walnut halves into filling. Place on plate.
Heat olive oil in large skillet over medium-high heat. Add mushrooms, round side down, and cook 5 minutes, or until mushrooms begin to release their juices and brown on bottom, shaking pan occasionally. Carefully add broth to pan, cover, and reduce heat to medium-low. Simmer 10 to 15 minutes, or until mushrooms are tender and filling has puffed and browned slightly. Remove mushrooms from pan, then add remaining 2 tsp. vinegar to pan. Simmer 1 to 2 minutes, or until sauce thickens slightly. Serve mushrooms drizzled with sauce.