For the sauce, in a blender, combine all the ingredients except the oil. Drizzle in the oil with the motor running and blend until smooth, then transfer to a small bowl and set aside. 

For the burgers, bring the quinoa, thyme and 2 cups cold water to a simmer in a small saucepan with lid over medium heat and cook for 15 minutes. Remove from heat and let sit, covered, for 5 minutes.  

Meanwhile, heat 2 tablespoons vegetable oil in a large saute pan over medium-high heat. Add the garlic and toast, then add the onions, poblanos and a pinch of salt, stir and cover. Cook until onions and poblanos soften, about 8 minutes. Uncover, reduce heat to medium-low and continue cooking, stirring often and scraping up any browned bits from the pan, until onions caramelize.  

In a large bowl, stir together the onion mixture, mushrooms, corn, red peppers and cooked quinoa. Pulse the black beans and chickpeas in a food processor until the mixture resembles quinoa grains. Transfer to the large bowl, add the egg, panko, lemon juice, cumin, curry powder, Dijon mustard, smoked paprika, cayenne, and salt to taste. Stir until well combined. 

Shape mixture into 12 thin patties and place on a parchment-lined baking sheet. Working in batches, cook on both sides in a well-oiled nonstick pan over medium heat until browned and heated through. Serve each patty on a burger bun with lettuce, tomato and cilantro avocado sauce. (If you don't want to serve all the patties at once, they freeze well.)