For the stuffed poblanos:
In a medium-size saucepan, heat 2 tablespoons of the canola oil over medium-high heat and when hot, saute the onions, bell pepper, and garlic for 3 to 4 minutes. Add the tomato paste, cumin, chili powder, and pepper flakes and cook until well blended, about 2 minutes longer. Pour the beer into the pan and cook, stirring, until nearly all the liquid evaporates.
Remove the pan from the heat and stir in the quinoa, beans, scallions, lime zest, and cilantro.
Preheat the oven to 350° F. Lightly spray a baking sheet with canola oil spray.
Put the poblano peppers, cavity side up, on the baking sheet and coat each lightly with the remaining tablespoon of canola oil (you may not need the entire tablespoon), and season with salt and pepper, to taste. Spoon about 1/2 cup of the quinoa stuffing into each pepper. Top with the shredded cheese and bake until the cheese melts and the pepper is soft, 10 to 12 minutes.
For the romesco sauce:
Preheat the oven to 375° F. Lightly spray a baking sheet with canola oil spray.
In a large bowl, toss together the tomatoes, bell peppers, garlic, and canola oil. Spread the vegetables on the baking sheet and roast until the peppers begin to soften, 10 to 15 minutes. Watch carefully so that the garlic does not burn.
In the bowl of a food processor fitted with the metal blade, process the roasted vegetable mixture with the bread, almonds, vinegar, and dried pepper flakes for 2 to 3 minutes or until fairly smooth but not completely pureed. Turn off the food processor and scrape down the sides. Season to taste with salt and pepper.
With the processor running, drizzle the olive oil through the feed tube as the sauce emulsifies. If the sauce is too thick, thin it with a little water, 1 teaspoon at a time.