2 (14-ounce) cans of lentils, drained and rinsed*
1 cup walnuts, finely chopped
2 teaspoons extra-virgin olive oil
2 cups finely chopped sweet onion
3 garlic cloves, minced
1 cup finely chopped celery
1 cup grated carrot
1/3 cup peeled and grated sweet apple
1/3 cup dried cranberries (chopped) or raisins
2 teaspoons fresh thyme (or 1 teaspoon dried thyme)
1 teaspoon dried oregano
Fine sea salt, to taste (I use about 1 teaspoon)
Freshly ground black pepper, to taste
3 tablespoons ground flax
1/2 cup oat flour
1/2 cup spelt bread crumbs (or bread crumbs of choice)
1/4 teaspoon red pepper flakes (optional)
Preheat the oven to 325°F. Grease a 9x5-inch loaf pan, and then line it with a piece of parchment paper cut to fit the length of the pan.
If using canned lentils, rinse and drain them in a colander. If using lentils cooked from scratch, follow the directions in the note below. After draining, add them into a very large bowl and mash the lentils with a potato masher. The goal is to create a lentil paste while still leaving about 1/3 of the lentils intact.
Spread the chopped walnuts onto the baking sheet. Toast the nuts for 8 to 12 minutes until fragrant and lightly golden. Set aside to cool.
Increase the oven heat to 350°F.
Add the oil into a large skillet, and increase the heat to medium. Stir in the onion and garlic and season with a pinch or two of salt. Cook for 4 to 5 minutes until the onion softens.
Stir in the celery and carrot, and continue cooking for another few minutes.
Finally, stir in the grated apple, dried cranberries (or raisins), thyme, oregano, 1/2 teaspoon salt, and black pepper. Cook for a couple minutes longer.
Into the bowl with the mashed lentils, stir in the walnuts, ground flax, oat flour, and bread crumbs until combined.
Stir in all of the the veggie mixture until combined. Add the red pepper flakes, if using. Taste and add more salt (I usually add another 1/2 teaspoon). If the mixture seems dry, add a tablespoon or two of water and mix again.
Press all of the lentil loaf mixture into the prepared loaf pan. Pack it down as firmly as you can as this will help it hold together after cooling.
In a small bowl, whisk together the ketchup, applesauce, vinegar, and maple syrup until combined. Using a pastry brush (or simply a spoon), spread all of the glaze over top of the lentil loaf.
Bake the lentil loaf, uncovered, at 350°F for 50 to 60 minutes until the edges start to darken and the loaf is semi-firm to the touch. Place the loaf pan directly onto a cooling rack for 15 minutes. Then, slide a knife around the ends to loosen, and carefully lift out the loaf (using the parchment paper as "handles") and place it directly onto the cooling rack for another 30 minutes.
After cooling, carefully slice the loaf into slabs. Serve immediately. The loaf will continue to firm up as it cools. Some crumbling is normal if sliced while warm.