If the steak is not already very thin (about 1/8"–1/4"), place between plastic wrap and pound gently with a meat mallet or rolling pin until uniformly thin. Trim any large pieces of fat. Pat dry with paper towels.

Season the steak

Season both sides of each steak lightly with 1 tsp of the salt and half the black pepper, pressing seasoning into the meat.

Set up breading station

Place the flour in a shallow dish. In a second dish whisk together the eggs and milk. In a third dish combine breadcrumbs, grated Parmesan (if using), garlic powder, smoked paprika, remaining 0.5 tsp salt and remaining black pepper; mix well.

Bread the steaks

Working one at a time, dredge a steak in flour, shaking off excess. Dip into the egg mixture, letting excess drip off, then press into the breadcrumb mixture to coat thoroughly. Set on a wire rack while you finish the rest.

Fry the milanesas

Heat a large skillet over medium-high heat and add oil. When oil is shimmering (about 350°F if using a thermometer), add steaks in a single layer (do not overcrowd — cook in batches if needed). Fry 2–3 minutes per side until golden brown and cooked through (internal temp ~145°F for medium). Adjust heat as needed so crumbs brown but do not burn. Transfer to a paper towel-lined plate. If desired, add butter to the pan and baste the steaks quickly for extra flavor.

Rest

Let the milanesas rest 3 minutes so juices redistribute before serving or assembling sandwiches.

Chimichurri

Combine chopped parsley, cilantro (if using), oregano, and minced garlic in a bowl. Stir in red wine vinegar, olive oil, red pepper flakes, salt and lemon juice (if using). Taste and adjust salt or acidity. Let sit at room temperature at least 10 minutes to meld flavors (can be made ahead and refrigerated up to 24 hours).

Sandwich & Salad assembly

Prepare bread and veggies

If making sandwiches, slice the baguette lengthwise. Lightly toast cut sides in a hot pan or oven for 1–2 minutes until just crisp. Spread mayonnaise on one side if using. Layer lettuce and tomato slices where you will place the milanesa.

Assemble sandwich

Place a warm milanesa on the prepared baguette, spoon 1–2 tablespoons of chimichurri over the steak (or serve chimichurri on the side), add more lettuce/tomato as desired. Close the sandwich and press gently. Cut in half and serve.

Plate option

To serve milanesa on a plate, arrange 1–2 pieces of milanesa beside mixed salad greens dressed lightly with olive oil, red wine vinegar, salt and pepper. Serve chimichurri on the side and garnish with lemon wedges.

Finishing & serving

Serve immediately while the milanesa is still warm and crisp. Provide extra chimichurri at the table. Leftover milanesa can be reheated in a 375°F oven for 8–10 minutes to re-crisp.