While the onions caramelize, remove the stems and scrape the gills from the portobello mushrooms, then chop the mushrooms finely, along with the red onion and baby spinach for the patty mixture.

In a medium mixing bowl, mash half of the black beans using a potato masher or fork until mostly smooth with some chunks remaining. Mix in the remaining half black beans, red onion, baby spinach, mushrooms, ¼ cup Just Chipotle Mayo, breadcrumbs, garlic, cumin, salt and pepper.

Scoop about 1/3 cup of the black bean mixture and form into a slider patty, about 3-inches in diameter. Set on a parchment-lined baking sheet. Repeat until you’ve made 12 slider patties. Refrigerate the patties for about 30 minutes.

While the patties set, prepare the salsa. If using frozen raspberries, defrost them in a microwave or small skillet. Combine the raspberries, red onion, cilantro, jalapeño, garlic, beer (or lime juice), salt, pepper, cumin and sugar in a medium bowl. Gently mash the berries with a fork to release a bit of the berry juices. Leave large pieces of raspberry in the salsa as they will break down over time. Set the salsa aside and let the flavors meld for about 20 minutes.

Heat the remaining 2 tablespoons of olive oil in a large non-stick skillet over medium heat until shimmering. Add the patties, in batches if needed, and cook for about 4 minutes per side.

To assemble, spread Just Chipotle Mayo on the inside of the slider buns. Place a patty on the base of each bun. Top with a big pinch of caramelized onions and a spoonful of raspberry salsa. Serve!