Step 1

Sauté onion, garlic: Heat 1 tablespoon of grapeseed oil in a skillet over medium-high heat. Add onion, cook until golden brown on the edges, about 8 minutes. Add garlic and cook until fragrant, about 1 minute.

Step 2

Pulse mixture: Empty onion mixture into food processor. Add tahini, parsley, cilantro, cumin, coriander, lemon zest, salt, and pepper. Pulse until a paste. Add chickpeas and pulse until the mixture looks like a chunky batter (leave some bits of chickpea for texture).

Step 3

Stir and chill: Transfer the mixture to a large bowl. Stir in quinoa flakes until well mixed. Fold in feta. Cover and refrigerate for 15 minutes.

Step 4

Preheat: Preheat oven to 400°F (200°C)

Step 5

Tzatziki sauce: Meanwhile, grate cucumber on the large holes of a box grater. Transfer cucumber to a nutmilk bag or cheesecloth, squeeze out as much liquid as you can. Add cucumber, yogurt, dill, lemon juice, garlic, salt, and pepper to a bowl. Stir to mix. Cover and refrigerate until needed.

Step 6

Shape and bake patties: Line a baking sheet with parchment. Use your hands to shape 4 patties and place on baking sheet. Brush patties (both sides) with remaining 1 tablespoon grapeseed oil. You want the patties to be well oiled, so use a bit more if needed. Bake until golden brown and firm to the touch, about 30 minutes, flipping halfway.

Step 7

Assemble: Spread tzatziki on toasted buns. Stack with patties, fresh veggies of your choice, and more crumbled feta (if using).