1/2 Cup Red Or Black Quinoa, Rinsed
1/2 Cup Extra-Virgin Olive Oil, Divided, Plus More For Drizzling
2 (14.5-oz.) Cans Chickpeas, Rinsed, Drained
1 Tsp. Garlic Powder
1/2 Tsp. Smoked Paprika
8 Oz. Crimini Mushrooms, Trimmed, Cut Into 1/4″ Pieces
1/4 Cup Tahini
1/4 Cup White Miso
1/4 Cup Oat Flour Or All-Purpose Flour
8 Slices Sharp Cheddar Or Vegan Cheese (Optional)
Mayonnaise, mustard, hamburger buns, shredded iceberg lettuce, and sliced pickles (for serving; optional)
Cook quinoa in a large saucepan of lightly salted boiling water, stirring occasionally, until tender, 8–10 minutes. Drain well and let cool at least 10 minutes.
Meanwhile, heat 1/4 cup oil in a large nonstick skillet over medium-high. Add chickpeas (make sure they are well drained) and cook, tossing occasionally, until lightly browned, 8–10 minutes. Add garlic powder and paprika and toss a few times to coat. Transfer to a large bowl and let cool about 5 minutes.
Add mushrooms, tahini, miso, and 1/4 cup oil to bowl with chickpeas and mash with a potato masher or fork to combine. Add quinoa and flour and mash until mixture holds together when squeezed in your hand. Taste and season with salt if needed. Form into 8 patties and arrange on a parchment-lined rimmed baking sheet. Freeze until firm, about 2 hours. At this point, the patties can be baked, or they can stay frozen up to 3 months. Transfer to resealable freezer bags or layer in an airtight container with sheets of parchment between patties.
Preheat oven to 425°. Drizzle frozen patties generously with oil on both sides on a rimmed baking sheet. Bake patties until browned and crisp, 25–30 minutes. Place a slice of cheese on top of each patty and bake until cheese is melted, about 1 minute.
Spread mayonnaise and mustard on cut sides of buns (if using). Place burgers on bottom buns. Top with lettuce and pickles (if using) and close up burgers.
Do Ahead: Patties can be made 3 months ahead. Transfer to a resealable freezer bag and freeze.