Serves 2-3
4 scallions, trimmed and thinly sliced crosswise (white and green parts)
2 small red onion, thinly sliced
1/2 cup lime juice (from 2 or 3 limes)
Kosher salt
4 tablespoons extra-virgin olive oil
Two 15.5-ounce can no-salt-added black beans, with the liquid
2 teaspoons chili powder
2 teaspoons ground cumin
2 teaspoons Spanish smoked paprika (pimentón; sweet or hot)
2 teaspoons Dijon mustard
Twelve 6-inch corn tortillas
2 cups chopped romaine lettuce (from 1 heart of romaine)
Hot sauce, such as Cholula (optional)
First, let’s make the two-onion quick pickle: Combine the scallions and half the red onion slices in a medium bowl. Here’s a trick to give you less onion breath (you’ll thank us later!): Cover the onions and scallions with hot tap water and squeeze them a few times with your hands. Let them stand for about 2 minutes to extract their raw flavor, then drain.
Combine the lime juice, the rinsed red onions and scallions, and the pinch of kosher salt in a small jar or liquid measuring cup. Let stand while you make the remainder of the recipe, or for at least 10 minutes.
On to the black beans: Heat the oil until shimmering in a large skillet over medium heat. Add the remaining red onion and cook without stirring for about 3 minutes, until lightly browned. Add the black beans with their liquid, the chili powder, cumin, Spanish smoked paprika, Dijon mustard and 1/2 teaspoon of kosher salt; stir to incorporate. Cook for 5 to 7 minutes, stirring occasionally, until the liquid reduces to a thick sauce and your kitchen smells heavenly.
We like to add a bit of flavor and lovely char marks while warming our tortillas (not required, but highly recommended). Place a tortilla right on the grate above the flame of a gas burner, then cook on medium heat for a few seconds per side, flipping with tongs, until lightly blackened on the edges. Repeat for all tortillas. If you don’t have a gas range, arrange the tortillas in a single layer on a baking sheet and broil for about 1 minute per side.
To assemble the tacos, place some chopped romaine at the center of each tortilla, then add a large spoonful of the black bean mixture. Top with the pickled red onion and hot sauce, if using. If desired, you can pour a small splash of the lime juice from the onion pickle onto each taco (but be conservative, or you’ll have a watery taco).