Heat 2 inches of vegetable oil to 350F in a deep pan or pot. Fry potato strips in batches until golden and crispy, about 5-6 minutes per batch. Drain on paper towels and salt immediately.

Season the sirloin steak strips with salt and pepper. Heat a wok or cast iron pan until screaming hot. Cook the beef in small batches, searing for 60-90 seconds per batch until deeply browned. Remove and set aside.

In the same hot pan, add a splash of oil if needed, then add the onion wedges. Toss for 30 seconds. Add minced garlic and sliced aji amarillo peppers (or paste), and stir for 15 seconds until fragrant.

Add the tomato wedges, 3 tbsp soy sauce, 2 tbsp red wine vinegar, and oyster sauce to the pan. If using pisco or brandy, add it now and allow it to flame off. Toss for 30 seconds.

Return the seared beef to the pan. Toss everything together for 15-20 seconds until the sauce coats all ingredients in a glossy glaze.

To serve, pile the lomo saltado stir-fry on one side of a plate, the crispy fries on the other, and cooked white rice alongside. Garnish generously with fresh cilantro.