Start by making the pickled onions. Peel and cut the onion into even 1/8" slices. Place in a heat-safe jar like a pint mason jar. In a pot, combine the vinegar, water, sugar, and salt. Bring the mixture to a boil, remove from the heat, and pour over the onions. Let the onions sit while making everything else.

Next, make the cabbage slaw. Combine the slaw, sliced scallions, and cilantro in a bowl. Squeeze the lime juice over the cabbage, add in the olive oil, and salt. Toss to combine and coat everything evenly.

Finally, heat a pan over medium-low heat. Add the olive oil followed by the minced garlic. Cook the garlic until golden then add in the pinto beans. Cook for a minute or two more, just to warm the beans.

Assemble the tacos with 1/4 cup of the beans, 1/4 of the cabbage, some pickled onions, and toasted pepitas to finish.