- 3/4 cup uncooked brown or green lentils*
- 1 1/2 cups water
- 2 tablespoons cider vinegar
- 1 tablespoon extra-virgin olive oil (plus more for frying the burgers, as needed)
- 1 cup finely minced onion
- 2 teaspoons minced garlic
- 1 teaspoon dry mustard
- 10 mushrooms (about 2-inch diameter), minced
- 3/4 teaspoon salt
- 1/2 pound baby spinach, finely minced (optional)
- Freshly ground black pepper to taste
- 1/2 cup finely minced California walnuts
- 1 cup whole-wheat breadcrumbs (from toasted whole-wheat sandwich bread)
- Grated Cheddar for melting on top (optional)
*Although the recipe calls for lentils, try making them with yellow split peas as well, for a lovely and sturdy variation. The split peas will need a little more water (up to 2 1/2 cups) and more cooking time, but are a really nice option.