Make the mojo marinade: In a small bowl whisk together the orange juice, 1 tbsp extra-virgin olive oil, minced garlic, ground cumin, dried oregano, 3/4 tsp salt and 1/4 tsp pepper (and a pinch of smoked paprika or chipotle if you want smoke/heat). This bright, garlicky emulsion brings acid (orange) to tenderize the pork and fat (oil) to carry flavor; the aromatics (cumin/oregano) give the pork its Cuban-inspired character.

Reserve 1 tablespoon of mojo per person (4 tablespoons / ~60 ml) in a small bowl for finishing/assembling the tacos. Use the remainder to marinate the pork. Pat the 600 g pork tenderloin dry and season lightly with 1 tsp kosher salt and 1/2 tsp black pepper. Pour the mojo over the pork and rub it into the surface. Let the pork marinate at room temperature for 10–15 minutes while you prep other elements (the acid in the mojo shortens needed marinating time and helps flavor penetrate).

Quick-pickle the cabbage: Put the 240 g shredded red cabbage in a bowl or jar. In a small saucepan bring 60 ml vinegar, 60 ml water, 1 tbsp sugar and 3/4 tsp kosher salt to a simmer to dissolve the sugar and salt (heating mellows the vinegar and helps dissolve the sugar). Pour the hot liquid over the cabbage, press the cabbage down so it's submerged, and let sit at least 15–20 minutes while you cook. This softens the cabbage just enough to add crunch and tang without losing its fresh texture.

Warm and season the black beans: Put the 320 g cooked black beans in a small skillet with a pinch of salt and a tablespoon of the reserved mojo (or a splash of the pickling liquid if you prefer). Gently warm over medium-low heat for 3–4 minutes, mashing about one-third of the beans with the back of a spoon to create a mix of whole and creamy texture that clings to the tortilla. Warming melds the beans with the mojo flavors and lets starches thicken slightly for better mouthfeel.

Sear the pork tenderloin: Heat a heavy skillet (cast-iron recommended) over medium-high heat until shimmering. Add 1 tbsp olive oil and when it glows add the marinated pork. Sear 2–3 minutes per side, turning to get an even golden-brown crust — that Maillard browning adds savory depth and texture. After all sides are browned, reduce heat to medium and continue cooking, turning occasionally, until an instant-read thermometer registers 58–60°C (137–140°F) for medium-rare to medium (internal temperature will rise a few degrees while resting). This timing should be ~6–8 minutes after searing, depending on thickness. Do not overcook — pork tenderloin is very lean and will dry out if pushed past 65°C.

Rest and slice the pork: Transfer the pork to a cutting board and rest 5–7 minutes to let juices redistribute — slicing immediately will cause juices to run out and make the meat drier. Slice crosswise into 1/4-inch (6 mm) slices; the thin slices are tender and easy to eat in tacos.

Finish the pork (optional gloss): Return the skillet to medium heat and add the reserved 1 tbsp mojo per person (total ~4 tbsp) with 1 tsp butter; swish to warm and deglaze the pan with any browned bits, then briefly toss the sliced pork in the hot mojo for 30 seconds to coat and concentrate flavor — this step accentuates the citrus-garlic aromatics and gives a glossy finish.

Warm the tortillas: Heat a clean skillet or comal over medium-high. Warm corn tortillas 20–30 seconds per side until pliable and slightly charred in spots. Keep warm wrapped in a clean kitchen towel or foil — warm tortillas fold better and release more aroma.

Assemble the tacos: On each tortilla, spread about 80 g warmed black beans, add 150 g equivalent of sliced pork per person (150 g raw yields the listed portion once cooked; portion the slices so each person gets roughly 150 g), top with 60 g quick-pickled cabbage, sprinkle with 5 g chopped cilantro, and finish with a squeeze of 1/4 lime and an extra drizzle of reserved mojo if desired. The interplay of warm, savory pork and beans with bright, acidic cabbage makes each bite layered and lively.

Serve immediately with extra lime wedges and hot sauce or pickled jalapeños on the side. Encourage guests to squeeze their lime just before eating — the acid brightens all the flavors.