Lomo Saltado Steak Fries with Tangy Peruvian Sauce

Lomo saltado steak fries bring together crisp fries, seared beef, red onion, tomato, and a savory, tangy sauce inspired by Peru’s lomo saltado. Serve them piled on a platter while the fries are hot, so the juicy stir-fry flavors coat some fries without turning the whole batch soggy.

Ingredients

1½ lb (680 g) russet potatoes, scrubbed
2 tbsp (30 ml) neutral oil, such as avocado or canola oil, for the potatoes
1 tsp fine salt, divided, plus more to taste
1½ lb (680 g) beef sirloin or strip steak, trimmed and cut across the grain into strips about ¼ inch (6 mm) thick
1 tbsp (15 ml) neutral oil, for searing the beef
1 medium red onion (about 8 oz/225 g), cut into thick wedges
2 medium Roma tomatoes (about 8 oz/225 g), cut into wedges
2 garlic cloves (about 6 g), finely chopped
3 tbsp (45 ml) soy sauce
2 tbsp (30 ml) red wine vinegar
1 tbsp (15 ml) aji amarillo paste, plus more to taste; use yellow bell pepper strips and a pinch of mild chili flakes if unavailable, though the sauce will be less fruity and complex
¼ cup (60 ml) beef broth or water
2 tsp (10 ml) cornstarch
2 tbsp (30 ml) chopped fresh cilantro leaves
2 scallions (about 30 g), thinly sliced, for serving
1 lime, cut into wedges, for serving

Instructions

Heat the oven to 425°F (220°C). Line a large rimmed baking sheet with parchment. Cut the potatoes lengthwise into fries about ⅜ inch (1 cm) thick. Pat them thoroughly dry with a clean towel; dry potatoes brown more readily and are less likely to steam.
Toss the fries with 2 tablespoons (30 ml) oil and ½ teaspoon salt. Spread them in one layer with space between pieces, using two pans if needed. Roast for 25–30 minutes, turning once after about 15 minutes, until browned and tender. Timing varies with thickness and oven; check the thickest fries with a fork.
While the potatoes roast, pat the steak dry and season it with the remaining ½ teaspoon salt. Stir the soy sauce, vinegar, aji amarillo paste, broth, and cornstarch together in a small bowl until smooth. Keep the steak and sauce separate until cooking.
Heat a large skillet or wok over high heat until very hot, then add 1 tablespoon (15 ml) oil. In two batches, sear the steak in a single layer for about 1 minute per side, just until browned. Avoid crowding the pan, which lowers its temperature and steams the meat. Transfer each batch to a clean plate; the beef will finish cooking in the sauce.
Add the onion to the hot skillet and stir-fry for 1–2 minutes, keeping it crisp-tender. Add the tomatoes and garlic and cook for about 1 minute, until fragrant and the tomatoes begin to soften but still hold their shape.
Pour in the sauce mixture and stir for 30–60 seconds, until it thickens and bubbles. Return the steak and any juices to the pan; toss just long enough to coat and heat through. Check the thickest beef strips with a food thermometer: USDA FSIS safe minimum for whole cuts of beef is 145°F (63°C), followed by a 3-minute rest. If the beef has not reached that temperature, continue cooking and check again. The strips can cook quickly, so avoid leaving them in the pan longer than necessary.
Remove the skillet from the heat and fold in the cilantro. Taste the sauce and add a little salt or vinegar if needed. Arrange the hot fries on a platter, spoon the beef and vegetables over them, and scatter the scallions on top. Serve immediately with lime wedges.

Tips

For crisp fries, dry the cut potatoes well and leave space between them on the pan. If your oven cannot accommodate two pans without crowding, roast the fries in batches.
Slice the beef across the grain, and keep the strips a similar thickness so they sear evenly. A very hot pan and small batches help create browned edges without overcooking the beef.
Aji amarillo is a Peruvian yellow chili paste with fruity heat, available in some Latin American shops and online. The suggested bell pepper substitute keeps the color and sweetness but gives less chile flavor; add chili flakes cautiously.
For less-soggy fries, keep the fries and beef mixture separate until everyone is ready to eat. Set out extra sauce at the table rather than pouring all of it over the platter at once.

Serving Suggestions

Serve the fries as a filling main dish for four, with extra lime wedges so each person can brighten the rich beef and salty potatoes to taste. A simple green salad, sliced avocado, or steamed green beans makes a refreshing side. For a more traditional lomo saltado-style meal, offer rice alongside the fries; the rice is useful for catching any sauce left on the plate.

Variations

Use frozen oven fries when short on time, preparing them according to their package directions before adding the topping. For a milder dish, reduce the aji amarillo paste to 1 teaspoon or omit it; for more heat, add a small amount of chili flakes. You can replace sirloin with strip steak, flank steak, or another tender beef cut, slicing it across the grain. For a vegetarian variation, use thick strips of firm, well-drained tofu or sliced mushrooms and cook until browned; the beef temperature guidance does not apply to those substitutions.

Storage and Reheating

For best texture, store leftover fries and beef topping separately in airtight containers and refrigerate within 2 hours of cooking. They keep for 3–4 days in the refrigerator. Reheat the beef mixture in a skillet over medium heat, stirring until it reaches 165°F (74°C); add a splash of water if the sauce has thickened too much. Reheat fries in a 400°F (205°C) oven or air fryer until hot and crisp. A microwave is convenient but makes fries soft. Assemble only the portion you plan to eat, and discard food left at room temperature for more than 2 hours.

Frequently Asked Questions

Can I make the fries in an air fryer?
Yes. Work in batches so the fries sit in a mostly single layer, and follow your appliance’s directions, shaking the basket periodically. Cook until browned and tender; exact time depends on the fryer and fry thickness. Keep cooked batches warm in a low oven while you prepare the beef.

Can I prepare any part ahead?
You can cut the potatoes and keep them submerged in cold water in the refrigerator for up to 24 hours. Drain and dry them very thoroughly before roasting. You can also mix the sauce ahead and refrigerate it, covered, for up to 1 day; stir again before adding it to the pan.

Why did my fries turn soggy?
They may have been crowded, insufficiently dried, or covered with sauce too early. Roast in a single layer and pile on the beef mixture just before serving. The tomatoes and sauce naturally soften the fries they touch, so serve the dish promptly.

What cut of beef works best?
Sirloin and strip steak are convenient, tender choices for quick searing. Flank steak also works when sliced thinly across the grain. Avoid very thick pieces, which take longer to cook and are harder to keep tender in a fast stir-fry.

Is this the same as traditional lomo saltado?
It is a steak-fries adaptation inspired by the Peruvian stir-fry. Lomo saltado is commonly served with both rice and fries, though ingredients and serving styles vary. This version puts the fries front and center for an easy platter-style meal.

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Safety notes: safe minimum internal temperatures from USDA FSIS; raw and undercooked fish guidance from the U.S. FDA. Food safety notes

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