Preheat oven to 400 degrees and line a baking sheet with foil or use a non-stick baking pan. Place a colander in the sink. Thoroughly rinse produce and pat dry. Mince garlic. Peel and finely dice red onion. Finely chop walnuts. Cut radishes into thin rounds. Drain pickled jalapeños, reserving juice. Finely shred romaine heart. Drain and rinse black beans.

In a mixing bowl, add walnuts, garlic, apple cider vinegar, 1 tsp. olive oil, half the tostada spice blend (to taste, reserving the rest for crema), and a pinch of salt and pepper. Stir and mash together until spices are evenly distributed. Traditionally made with pork, walnuts make a great meatless version of this spicy Mexican sausage.

Arrange 6 tortillas in a single layer on baking sheet and lightly brush each side with a little olive oil. Bake for 5 minutes, flip tortillas, and bake for another 5 minutes, or until crisp. Remove from oven and set aside.

Warm 1 tsp. olive oil in a medium pan over medium heat. Add half the red onion and cook until softened, about 3-4 minutes. Add black beans, smashing them until slightly creamy and smooth, about 2 minutes. Stir in 1 tsp. of water at a time until a spreadable consistency is reached. Season to taste with salt and pepper and set aside.

In a small bowl, mix sour cream and remaining tostada spice blend. For a slightly thinner consistency, add 1-2 tsp. water or reserved jalapeño juice to taste, depending on your preference for spice. Season with a pinch of salt and pepper. Pickled jalapeño juice will carry some bite from the peppers and vinegar, so add judiciously.

Arrange 3 tortillas on a plate. Slather tortillas with smashed black beans. Top with a generous spoonful of walnut chorizo. Drizzle with spiced crema. Garnish with romaine, radish, remaining red onion, and pickled jalapeños.