Lomo al Trapo with Cilantro-Lime Ají and Papas

Why You’ll Love This Recipe

• Classic Colombian technique: a salt-crusted cloth seals in juices for incredible tenderness.
• Minimal seasoning, maximum flavor: pure beefy taste with a smoky kiss from the embers.
• A complete plate: buttery papas criollas, creamy guacamole, and a bright cilantro–lime ají.
• Surprisingly approachable at home with clear steps and make-ahead options.

Grocery List

• Produce: 2 lb papas criollas or small yellow potatoes, 3 avocados, 1 small tomato, 1 jalapeño or serrano, 1 bunch cilantro, 3–4 limes, 2 scallions, 1 garlic clove
• Dairy: None
• Pantry: Coarse kosher or rock salt (3 lb), dry red wine (optional), olive oil, neutral frying oil, black pepper, fresh rosemary or thyme, white vinegar, sugar, kitchen twine, 100% cotton dish towel

Full Ingredients

Beef Tenderloin + Salt Crust

• 1 whole center-cut beef tenderloin, about 2.25 lb (1 kg), trimmed and patted dry
• 3 lb (1.36 kg) coarse kosher or rock salt
• 1 cup (240 ml) dry red wine or water (to dampen the cloth)
• 1/2 cup (120 ml) water (to dampen the exterior)
• 1 tbsp olive oil
• 2 tsp coarsely ground black pepper
• 1 tbsp finely chopped fresh rosemary (or 2 tsp fresh thyme)
• 100% cotton dish towel (about 16 x 24 inches) and kitchen twine

Papas Criollas

• 2 lb (900 g) papas criollas or small yellow potatoes
• 1/2 cup (120 ml) neutral oil (canola or sunflower) for frying
• 1 tsp kosher salt

Guacamole (Colombian-Style)

• 3 ripe Hass avocados
• 2 tbsp fresh lime juice (about 1 large lime)
• 1 small ripe tomato, seeded and finely diced
• 2 tbsp minced scallion (white and light green parts)
• 1/4 cup finely chopped cilantro
• 1 small jalapeño, finely minced (optional for heat)
• 1/2 tsp kosher salt

Cilantro–Lime Ají

• 1 cup (lightly packed, about 40 g) cilantro leaves and tender stems
• 2 scallions, roughly chopped
• 1 small serrano chile, seeded for mild or left with seeds for heat
• 1 small garlic clove
• 3 tbsp fresh lime juice
• 2 tbsp white vinegar
• 2 tbsp neutral oil
• 1/3 cup (80 ml) water
• 1/2 tsp kosher salt
• 1/2 tsp sugar

To Serve

• Lime wedges
• Extra cilantro leaves (optional)

Step-by-Step Instructions

Step 1: Build a bed of embers

Light a full chimney of charcoal. When the coals are fully ashed over (about 20 minutes), pour them into your grill or fire pit and spread into a flat, even bed of glowing embers 1–2 inches deep. You want no active flames—just steady, radiant heat. As a rule of thumb, you should only be able to hold your hand 5 inches above the embers for 3–4 seconds before it feels too hot.

Step 2: Parboil the potatoes

Meanwhile, place the papas criollas in a pot, cover with cold water by 1 inch, and add 1 teaspoon salt. Bring to a boil and cook until just tender when pierced, 12–15 minutes. Drain and let them steam-dry in the colander; this helps them crisp later.

Step 3: Make the guacamole and the cilantro–lime ají

Guacamole: In a bowl, mash the avocados with lime juice and salt. Fold in tomato, scallion, cilantro, and jalapeño (if using). Taste and adjust salt or lime. Press plastic wrap directly on the surface and chill.

Ají: In a blender, combine cilantro, scallions, serrano, garlic, lime juice, vinegar, oil, water, salt, and sugar. Blend until smooth and bright green. Chill until serving.

Step 4: Prep the beef and the cloth

Pat the tenderloin dry. Rub with olive oil, then sprinkle on all sides with black pepper and rosemary (or thyme). Lay a clean, 100% cotton dish towel on a board and evenly dampen it with 1 cup red wine or water. Spread the coarse salt over the towel in a rectangle just larger than the tenderloin, about 1/2 inch thick. Place the tenderloin centered on the salt.

Step 5: Wrap, tie, and dampen

Roll the towel tightly around the beef so the salt fully encases it. Fold the ends toward the center like a burrito. Tie with kitchen twine every 2 inches along the length and at the ends to make a snug log. Dampen the exterior with about 1/2 cup water so the towel is evenly moist (not dripping); this helps the salt harden into a shell.

Step 6: Roast directly on embers

Set the wrapped tenderloin directly on the bed of embers. If flames lick up, move to a calmer spot or gently fan out the flame—steady embers are key. Cook 28–35 minutes total, turning with long tongs every 8–10 minutes so the crust chars evenly. For medium-rare, begin checking at 25 minutes by inserting a thin instant-read thermometer through the end of the log into the center; pull at 120–125°F (49–52°C). For medium, pull at 130–135°F (54–57°C).

Step 7: Crisp the potatoes while the beef finishes

Heat 1/2 cup neutral oil in a large skillet over medium-high until shimmering. Add the parboiled potatoes and sauté, shaking the pan occasionally, until golden and crisp, 8–10 minutes. Season with 1 teaspoon salt. Keep warm.

Step 8: Rest, crack, and slice

Transfer the wrapped beef to a sheet pan or board and rest 10 minutes. Using the back of a knife, crack the hardened salt shell, cut the twine, and peel off the charred cloth. Brush away any loose salt. Slice the tenderloin into 1-inch (2.5 cm) thick medallions. Plate with papas criollas, a generous spoon of guacamole, and a dish of cilantro–lime ají. Serve with lime wedges.

Pro Tips

• Use only a 100% cotton towel. Synthetics can melt or smoke excessively.
• Choose coarse salt. Fine salt compacts too tightly; coarse grains form a breathable shell.
• Wine vs. water: Red wine lends a traditional tint and subtle aroma, but water works just as well.
• Embers, not flames: Move the log if you see flare-ups. Even radiant heat cooks the interior gently.
• Temperature check: Insert a thin probe from the end of the log to minimize salt intrusion.

Variations

• Gas grill adaptation: Preheat on high for 15 minutes, then turn burners to low. Place the wrapped log directly over the hot flavorizer bars or on a bed of preheated lump charcoal set in a perforated pan; cook as directed, turning often.
• Herb and spice accents: Add crushed coriander or whole peppercorns under the beef before rolling for a more aromatic crust.
• Oven back-up: If the weather turns, place the wrapped log on a rimmed sheet and roast at 500°F (260°C) for 25–35 minutes, turning once; the crust will char less but the method still works.

Storage & Make-Ahead

Ají keeps 3 days refrigerated in a sealed jar. Guacamole is best the day it’s made; to hold up to 24 hours, press plastic wrap directly on the surface and refrigerate. Parboil potatoes up to 24 hours ahead; cool, refrigerate, then crisp just before serving. Leftover beef slices keep 3–4 days refrigerated; rewarm gently in a 275°F (135°C) oven, wrapped in foil, until just warmed through, or enjoy cold in sandwiches.

Nutrition (per serving)

Approximate: 570 calories; 34 g fat; 32 g carbohydrates; 37 g protein; 7 g fiber; 780 mg sodium. Values will vary based on oil absorption and how thoroughly you brush off excess salt.