This taco recipe from KCET's America's Test Kitchen makes a pretty close approximation of the excellent truck tacos we have all around L.A. Even if you don't want steak, you'll want the limes and radishes and other trimmings, and you'll definitely want the pickled onions recipe.
Steak Tacos With Pickled Onions
Serves 4 to 6
1/2 cup packed fresh cilantro leaves
3 medium garlic cloves, roughly chopped
3 medium scallions, roughly chopped (about 1/3 cup)
1 medium jalapeño chile, stemmed and roughly chopped (see note)
1/2 teaspoon ground cumin
1/4 cup vegetable oil
1 tablespoon fresh lime juice
1 flank steak (1 1/2 to 1 3/4 pounds), trimmed of excess fat and cut lengthwise (with grain) into 4 equal pieces (see below)
1 tablespoon kosher salt or 1 1/2 teaspoons table salt
1/2 teaspoon sugar
1/2 teaspoon ground black pepper
2 tablespoons vegetable oil
12 (6-inch) corn tortillas, warmed (see note)
Fresh cilantro leaves
Minced white or red onion
1 red onion, halved and sliced thin
1 cup red wine vinegar
1/3 cup sugar
2 jalapeno chiles, stemmed and cut into rings
1/4 tsp. salt
For the pickled onions: Place the onions in a medium heat-resistant bowl. Bring the vinegar, sugar, jalapenos and salt to a simmer over medium-high heat, stirring occasionally until sugar dissolves.
Pour the vinegar mixture over the onions, cover loosely with plastic wrap and let cool to room temperature (about 30 minutes). Once cool, drain the liquid and store in the refrigerator for up to 1 week.
For the herb paste: Pulse cilantro, garlic, scallions, jalapeño, and cumin in food processor until finely chopped, ten to twelve 1-second pulses, scraping down sides as necessary. Add oil and process until mixture is smooth and resembles pesto, about 15 seconds, scraping down sides of workbowl as necessary. Transfer 2 tablespoons herb paste to medium bowl; whisk in lime juice and set aside.
For the steak: Using dinner fork, poke each piece of steak 10 to 12 times on each side. Place in large baking dish; rub all sides of steak pieces evenly with salt and then coat with remaining herb paste. Cover with plastic wrap and refrigerate at least 30 minutes or up to 1 hour.
Scrape herb paste off steak and sprinkle all sides of pieces evenly with sugar and pepper. Heat oil in 12-inch heavy-bottomed nonstick skillet over medium-high heat until smoking. Place steak in skillet and cook until well browned, about 3 minutes. Flip steak and sear until second side is well browned, 2 to 3 minutes. Using tongs, stand each piece on a cut side and cook, turning as necessary, until all cut sides are well browned and internal temperature registers 125 to 130 degrees on an instant-read thermometer, 2 to 7 minutes. Transfer steak to cutting board and let rest 5 minutes.
For the tacos: Using sharp chef's knife or carving knife, slice steak pieces across grain into 1/8-inch-thick pieces. Transfer sliced steak to bowl with herb paste-lime juice mixture and toss to coat. Season with salt. Spoon small amount of sliced steak into center of each warm tortilla and serve immediately, passing toppings separately.