• Add the beets to a steamer basket over boiling water and cover. Steam for 20–25 minutes, or until tender. Set aside to cool slightly.
• Preheat the oven to 350°F and line a baking sheet with parchment paper.
• Add the lentils, onion, sunflower seeds, parsley, ground flaxseed, garlic, and cooked beets to a food processor. Pulse 6–7 times, or until a coarse mixture forms. Do not overmix.
• Scoop out approximately 1/2 cup of the mixture at a time and form into patties about 4–5 inches in diameter. Place each patty on the prepared baking sheet.
• Bake for 30 minutes, carefully flipping the patties halfway through.
• To serve, top each burger patty with sliced avocado and use a few romaine leaves as a bun. Enjoy!

Notes

• Leftovers: Refrigerate in an airtight container for up to 5 days, or freeze for up to one month. Enjoy cold or reheat on the stovetop or in a toaster oven.