3/4 cup brown lentils, rinsed, strained and picked through
1 3/4 cups plus 1 tablespoon low-sodium vegetable broth or water
2 teaspoons extra-virgin olive oil
1 large red onion, half finely chopped and half thinly sliced
Juice of 1/2 lemon
8 ounces fresh baby spinach
2 large cloves garlic, minced
Freshly ground black pepper
1/2 teaspoon ground cumin
1 cup whole-wheat breadcrumbs
1/2 cup walnuts, toasted and finely chopped
6 whole-grain vegan hamburger buns
Baby arugula, basil, roasted red bell peppers and spicy mustard, for serving, optional
A medium saucepan set over high heat should be used to bring the lentils and 1 3/4 cups of the stock to a boil. Reduce heat to medium-low, partially cover, and simmer for about 30 minutes, or until lentils are completely softened and liquid is absorbed. Use a potato masher to thoroughly combine with the remaining 1 tablespoon of liquid in a medium bowl. Place aside.
Over medium heat, warm the oil in a sizable nonstick skillet. Stirring often, add the chopped onion, lemon juice, and 1/4 teaspoon salt. Cook for about 6 minutes or until softened. Stir in the spinach, 1 1/2 teaspoons of black pepper, cumin, and garlic for about 3 minutes, or until the spinach wilts.
Mix the lentils thoroughly before adding the spinach combination, breadcrumbs, walnuts, and 3/4 teaspoon salt. For at least an hour or overnight, cover and chill.
Preheat the grill to medium-high heat. Cooking spray should be applied to both sides of the six 4-inch patties you formed from the ingredients. Grill for about 3 minutes per side, or until lovely grill marks appear. Assorted toppings can be added to the buns along with the patties, as desired.