Chimichurri Steak Sandwich Recipe

Roughly chop parsley, cilantro and oregano. Place herbs and minced garlic in a bowl or small food processor.

Add red wine vinegar, lemon juice (if using), red pepper flakes, salt and black pepper. Pulse briefly in the processor or stir to combine.

Slowly stream in olive oil while pulsing (or whisking) until emulsified but still slightly chunky. Taste and adjust seasoning; set aside at room temperature for at least 15 minutes to let flavors meld. Reserve about 1/4 cup for finishing sandwiches and 3 tbs for marinating steak.

Pat the skirt steak dry with paper towels. Season both sides evenly with kosher salt, smoked paprika and black pepper.

Rub 3 tbs of the prepared chimichurri over both sides of the steak and let rest at room temperature for 15–20 minutes (or refrigerate up to 2 hours).

Heat a heavy skillet or cast-iron pan over high heat until very hot. Add 1 tbs olive oil and swirl to coat.

Sear the steak 2–3 minutes per side for medium-rare (internal temp ~130–135°F / 54–57°C), adjusting time for thickness. Use tongs to sear edges briefly if needed. Do not overcrowd the pan.

Transfer steak to a cutting board and let rest 8–10 minutes so juices redistribute. Slice thinly against the grain into 1/4-inch strips.

While the steak rests, heat a large skillet over medium-low heat. Add butter and 1 tsp olive oil until melted and shimmering.

Add the thinly sliced onion and a pinch of salt. Cook slowly, stirring occasionally, about 12–18 minutes, until softened and golden-brown. Add the brown sugar and continue cooking 2–3 minutes to aid caramelization.

If onions begin to stick, add the balsamic vinegar and scrape the pan to deglaze. Taste and season with salt and pepper. Remove from heat.

If using jarred roasted red peppers, slice into 1/4-inch strips. Gently warm them with the caramelized onions for 1–2 minutes to combine flavors; if using whole roasted peppers, peel, seed and slice before warming.

Preheat oven broiler to high (or a toaster oven). Lightly butter the cut sides of the ciabatta pieces and place on a baking sheet, cut side up.

Broil the bread 1–2 minutes until golden and crisp—watch carefully to avoid burning.

Spread a thin layer (about 1–2 tbs) of chimichurri on each toasted ciabatta piece.

Arrange a layer of sliced skirt steak across each open face, dividing evenly.

Top the steak with a generous spoonful of caramelized onions and warmed roasted red pepper strips.

Crumble creamy blue cheese over the toppings (about 3–4 tbs per sandwich) so it softens slightly from residual heat.

Finish with an extra drizzle of chimichurri (about 1 tbs per sandwich) and garnish with fresh parsley leaves.

Serve open-face immediately while warm.