Heat a large pot over medium-low. Once hot, add the oil, then add the onion, celery, and garlic. Cook, stirring occasionally, for 10 minutes. The onion should be translucent. Turn the heat down if it's sticking or browning too much.
Stir in the spices, then add the crushed tomatoes and stir to combine. Add the beans, broth, and lentils.
1 teaspoon hot pepper flakes, ½ teaspoon sea salt, ½ teaspoon cumin, ½ teaspoon black pepper, 65 grams crushed tomatoes (passata), 350 grams cooked or canned black beans, 250 ml vegetable broth, 100 grams dried brown lentils
Cover the pot and increase the heat to bring the mixture to a boil. Reduce the heat and simmer, covered, for 30 minutes. After this time the lentils should have soaked up most of the broth.
Remove from the heat and mix in the rice, oats, almond flour, sunflower seeds, and parsley.
Take about a cup (this can be a measuring cup, or just use a mug, it doesn't matter) from the mixture and blend it in a food processor until smooth.
Add the pureed part back to the mixture and stir very well. You should have a rather sticky burger mixture at this point. Taste and season as needed.
Preheat the oven to 200°C (400°F) and line a large baking sheet with parchment paper. Brush the surface of the paper with a little oil.
Form eight evenly-sized patties, each about 1.5cm (⅔ in.) thick, and the width needed for the buns you're using. Place them onto the prepared baking sheet. Rinse your hands as needed to prevent sticking.
Bake the burgers for 20 minutes, carefully flipping at the halfway point. They should be golden around the edges and quite firm to the touch when ready.
Serve hot with desired toppings. Leftover burgers can be kept in a sealed container in the refrigerator for a couple of days but are best fresh.
Notes
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