Instructions

• Preheat the oven to 425°F (for the potatoes). Line a baking sheet with parchment paper.
• Prepare the rice: place 1 cup long-grain rice in a dry medium (about 2‑quart) saucepan over low heat. Toast, stirring occasionally, 5–6 minutes until the rice looks opaque and faintly milky. Add 2 cups minus 2 tablespoons boiling water, stir once, cover, and cook over low heat 12–15 minutes, until the water is absorbed and the rice is tender. Remove from heat, fluff with a fork, cover, and set aside.
• Cut the beef tenderloin into 1‑inch cubes. In a bowl, toss the beef with 1 tablespoon avocado oil and ½ teaspoon ground cumin (optional). Set the beef aside while you prepare the other components.
• Prepare the potatoes: peel the 2 pounds russet potatoes and cut into large batonnet (French fry) shapes. Toss the potato batons with 1 tablespoon avocado oil so they are evenly coated. Spread them in a single layer on the prepared baking sheet.
• Roast the potatoes: place the baking sheet on the middle rack of the preheated 425°F oven and roast 25–35 minutes, turning once halfway through, until the potatoes are golden and crisp. When done, reduce the oven temperature to 225°F and keep the potatoes on the baking sheet in the oven to stay warm while you finish the stir-fry.
• While the potatoes roast, combine the sauce: in a small bowl whisk together 3 tablespoons soy sauce, 1 tablespoon oyster sauce, 1 tablespoon distilled white vinegar, and ½ cup beef stock. Set aside.
• Heat a large (12‑inch) carbon‑steel pan, cast‑iron skillet, or wok over high heat until very hot. Add the remaining 3 tablespoons avocado oil and heat until shimmering.
• Add the beef in a single layer, spread it out, and cook undisturbed 90 seconds. Stir-fry the beef 30 seconds more, then transfer the beef to a large plate and set aside (reserve any juices on the plate).
• Return the hot pan to the burner (high heat), add the ½ peeled red onion cut into wedges and stir-fry about 2 minutes. Add the seeded julienne yellow bell pepper and the seeded julienne jalapeño and stir-fry 30 seconds. Add the 2 finely minced garlic cloves and cook just until fragrant (about 15–30 seconds).
• Push the vegetables to the side or leave them in the pan, then pour in the prepared soy–oyster–vinegar–stock mixture. Cook about 2 minutes over high heat to reduce slightly.
• Return the beef (and any accumulated juices) to the pan with the vegetables. Add the 3 seeded thickly sliced Roma tomatoes, 3 tablespoons minced fresh cilantro, and 1 teaspoon dry oregano (optional). Add the 3 green onions cut into 1‑inch pieces (optional). Stir or toss briefly just to combine and heat through, about 1 minute.
• Plate: serve the lomo saltado immediately with the cooked rice and the oven‑kept potatoes (fries).