Lamb Sirloin Steak Frites with Green Peppercorn Sauce
We are giving the classic bistro "Steak Frites" a serious upgrade by using tender lamb sirloin steak and a zesty, chilled green peppercorn labneh that cuts right through the richness. It is the kind of meal that feels fancy enough for a Saturday night but is straightforward enough to master in your own kitchen. You get that perfect, pan-seared crust on the lamb, the crunch of double-fried rosemary fries, and a bright celery-apple salad to keep everything feeling fresh. Let's get cooking!
Equipment
- Instant-Read Meat Thermometer for the steak
- A clip-on candy or deep-fry thermometer for the fries
Ingredients
The Lamb
- 4 lamb sirloin steaks fat trimmed down and scored, room temperature (6 to 7 oz / 170 to 200 g each)
- 1 teaspoon kosher salt
- ½ teaspoon freshly cracked black pepper
- 1 tablespoon neutral oil or rendered lamb fat
- 2 tablespoon butter unsalted
- 2 garlic cloves lightly crushed
- 3 sprigs fresh thyme
Green Peppercorn Labneh
- ¾ cup labneh or thick Greek yogurt
- 1 tablespoon green peppercorns in brine lightly crushed
- 1 teaspoon brine from the peppercorns
- 1 teaspoon lemon zest
- 1 tablespoon lemon juice
- 1 tablespoon olive oil
- 1 small garlic clove finely grated
- Pinch salt
Rosemary Fries
- 2 lbs russet potatoes 900 g
- 8 cups Neutral frying oil (canola, peanut, or sunflower) about 2 L
- 1 teaspoon kosher salt
- 1 teaspoon finely chopped fresh rosemary
For Serving
Instructions
Make the Green Peppercorn Labneh Sauce
- In a small bowl, whisk together the labneh, crushed peppercorns, brine, zest, juice, oil, garlic, and salt. Refrigerate until serving; it gets better as the flavours mingle.
Cut, Rinse and Dry Potatoes
- Cut potatoes into ⅜" (1 cm) thick fries. Rinse them in cold water to remove excess starch. Soak for 10 minutes, then drain and dry thoroughly with towels. Pro tip: Surface moisture is the enemy of crunch; ensure they are bone dry before frying.
Rosemary Fries - The First Fry (The Soften)
- Heat oil over medium-low heat until it reaches 300°F (150°C). If you don't have a thermometer, the oil is ready when a single test fry produces slow, gentle bubbles. Fry for 4 to 5 minutes until softened but still pale. This "blanching" step cooks the potato from the inside out. Remove and drain on a rack. Crucial Step: Let them rest and cool for at least 10 minutes to allow the starch to set.
Trim, Season & Sear the Lamb
- If your lamb has a particularly thick fat cap, trim it down to less than a ¼" and score diagonally, trying not to cut into the meat. If you prefer to keep the fat cap as is, see The "Cold Start" for Fat Rendering instructions.
- Season the room temperature lamb with salt and pepper.
- Heat a heavy skillet over medium-high heat with the neutral (high smoke point) oil. You want the pan surface at 425°F to 450°F (218°C to 232°C). The oil should be shimmering and just starting to show a faint wispy smoke. Sear in batches of two to prevent overcrowding and steaming. Place the lamb fat-cap down for 3 to 4 minutes to render. Flip and cook 2 to 3 minutes for a crust. You should hear a steady, active sizzle. If it sounds violent or looks smoky, turn the heat down slightly.
- Place the steaks on a sheet pan. Remove all but 1-2 tablespoons of the pan grease.
Butter Baste The Lamb
- Reduce the heat to medium (aiming for a pan temp of 350°F to 375°F / 177°C to 190°C). This is crucial! You want the butter to foam and smell nutty, not turn black and bitter. Add butter, garlic, and thyme. Once the butter melts, return all four steaks to the pan. Spoon foaming butter over the steaks for 2 to 3 minutes until the internal temp hits 125°F to 128°F (52°C to 53°C). Rest for 8 minutes, uncovered on a wooden board or warm plate.
Rosemary Fries - The Second Fry (The Crisp)
- Increase heat to medium-high until oil reaches 375°F (190°C). The oil should be shimmering and a test fry should sizzle vigorously immediately. Fry for 6 to 8 minutes until golden. This high heat creates a rigid, golden crust. Place the fries onto a sheet pan with a rack to let any extra oil drip off. Then transfer to a bowl and immediately toss with rosemary and salt.
For Serving
- Slice the lamb against the grain. Plate over a dollop of labneh green peppercorn sauce and serve with a side of hot rosemary fries and a crispy celery-apple salad.
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Video
Notes
Zimmy's Pro-Tips for the Perfect Lamb Sirloin
- Invest in an Instant-Read Meat Thermometer: When you're cooking lamb sirloin, 5 degrees is the difference between juicy medium-rare and overdone. A digital instant-read thermometer allows you to check the thickest part of the steak in seconds. For this recipe, pull the lamb at 125°F to 128°F; it will continue to rise as it rests!
- Oil Temperature is Non-Negotiable: For the fries, use a clip-on candy or deep-fry thermometer. If the oil is too cool, the potatoes will soak up the grease and become heavy. If it's too hot, the outside will burn before the inside is fluffy. Keeping it steady at 300°F for the first fry and 375°F for the second is the secret to success.
- The “Cold Start” for Fat Rendering: If your lamb has a particularly thick fat cap you can trim it down like we did, or you can place it fat-side down in a cold skillet, then turn the heat to medium-high. This allows the fat to melt (render) gradually as the pan heats up, resulting in a much crispier edge without overcooking the meat center.
- Don’t Crowd the Pan: If you are cooking all four steaks at once, make sure your skillet is large enough. If they are touching, they will steam instead of sear, and you'll lose that beautiful golden crust. Work in batches if you need to!
- Let It Breathe: When resting the lamb, do not tent it tightly with foil. This traps steam and will turn your perfectly crispy fat cap soft. Simply leave it on a warm plate or a wooden board; the meat is dense enough to hold its heat for those 8 minutes.
- Why Against the Grain? Look for the long muscle fibers in the lamb. Slice perpendicular to them. This “shortens” the fibers, making every bite melt-in-your-mouth tender rather than stringy.
- Learn Your Burners: Every stove is different. If you're using a stainless steel skillet, remember that it holds heat incredibly well. You may find that “Medium” on your stove actually acts like “Medium-High.” Use a thermometer to “calibrate” your senses the first few times you cook this!
- The Water Drop Test: If you don’t have an infrared thermometer for your skillet, flick a tiny drop of water onto the dry pan. If the water dances and skitters across the surface before evaporating, you've hit that perfect searing temperature of roughly 400°F to 450°F.
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