• 3/4 cup dried brown lentils, rinsed and picked over
• 2 1/2 tsp table salt
• 3/4 cup bulgur wheat
• 2 tbsp vegetable oil (canola, safflower, grapeseed, etc.)
• 2 medium onions, chopped fine (about 2 cups)
• 1 large celery rib, chopped fine (about 1/2 cup)
• 1 small leek, white and light green parts only, chopped fine (about 1/2 cup)
• 2 medium cloves garlic, minced or pressed through garlic press (2 teaspoons)
• 1 pound cremini or white button mushrooms, cleaned and sliced about 1/4 inch thick (about 6 1/2 cups)
• 15 oz canned black beans, rinsed and drained
• 1/3 cup mayonnaise (light works fine)
• 2 cups Japanese panko bread crumbs
• Ground black pepper

Instructions:

1. Bring 3 cups water, lentils, and 1 teaspoon salt to boil in medium saucepan over high heat; reduce heat to medium-low and simmer, uncovered, stirring occasionally, until lentils are just beginning to fall apart, about 25 minutes. Drain well in a mesh strainer. Line baking sheet with a layer of paper towels and spread drained lentils over. Gently pat lentils dry with additional paper towels; cool lentils to room temperature.
2. While the lentils simmer, bring 2 cups water and 1/2 teaspoon salt to boil in small saucepan. Stir bulgur wheat into boiling water and cover immediately; let stand off of the heat until water is absorbed, 20 minutes. Drain in fine-mesh strainer and use rubber spatula to press out excess moisture. Transfer bulgur to a medium bowl and set aside.
3. Heat 1 tbsp oil in 12-inch skillet over medium-high heat until shimmering. Add onions, celery, leek, and garlic; cook, stirring occasionally, until vegetables begin to brown, about 10 minutes. Transfer vegetable mixture to another medium bowl to cool and set aside. Add remaining 1 tbsp oil to now-empty skillet; heat over high heat until shimmering. Add mushrooms and cook, stirring occasionally, until golden brown, about 8-10 minutes. Add mushrooms to the bowl with the vegetable mixture; cool to room temperature, about 20 minutes.
4. Stir the bulger, black beans, and mayonnaise into the lentils and vegetable-mushroom mixture.  Transfer half of mixture to the food processor and pulse until coarsely chopped, about fifteen 1-second pulses; mixture should be cohesive but roughly textured. Transfer processed mixture to large bowl; repeat with remaining unprocessed mixture and combine with first batch. Stir in panko, 1 teaspoon salt, and pepper to taste. Line baking sheet with paper towels. Divide mixture into 12 portions, about 1/2 cup each, shaping each into tightly packed patty, 4 inches in diameter and 1/2 inch thick; set patties on baking sheet – the paper towels will absorb excess moisture. (Patties can be individually with plastic wrap and refrigerated up to 3 days.  Freezer instructions can be found below.)

To Cook on the Grill: Build medium-hot charcoal fire or preheat gas grill on high. Using tongs, wipe grate with wad of paper towels dipped lightly in vegetable oil. Grill burgers, without moving them, until well browned, about 5 minutes; flip burgers and continue cooking until well browned on second side, about 5 minutes. Serve.

To Cook on the Stove Top: Heat 2 tablespoons vegetable oil in 12-inch nonstick skillet over medium-high heat until shimmering; cook burgers, 4 at a time, until well browned, about 4 minutes per side, lowering heat to medium if browning too quickly. Repeat with additional oil and burgers. Serve. (Cooked burgers can be kept warm in 250-degree oven for up to 30 minutes.)

To Freeze: With freezing and defrosting, the patties increase in moisture content; it is therefore necessary to add more bread crumbs before freezing. For each burger to be frozen, add 1 teaspoon panko or 1/2 teaspoon plain bread crumbs to the mixture before shaping. Thaw the frozen patties overnight in the refrigerator on a triple layer of paper towels covered loosely with plastic wrap. Before cooking, pat the patties dry with paper towels and reshape to make sure they are tightly packed and cohesive.