Pat the steak very dry. Season all over with the salt and black pepper. Let it sit at room temperature for 30 minutes before cooking if the steaks are thick. Dry steak browns faster. If the surface is wet, the steak steams first and loses the hard sear that makes this salad feel steakhouse-level. That thorough drying matters directly because any residual moisture converts to steam the instant it meets the hot pan, working against the direct, sustained contact real browning depends on.

In a bowl or jar, combine the red wine vinegar, balsamic vinegar, Dijon, Worcestershire sauce, garlic, honey, salt, and black pepper. Whisk in the olive oil slowly until emulsified. Taste and adjust. The dressing should be sharp and savory, because it has to cut through rich steak and blue cheese. That deliberate sharpness is a genuine, functional requirement given how substantial this salad's other components are — a milder vinaigrette would be overwhelmed by the steak's own richness and the blue cheese's assertive tang rather than balancing them.

Toss the sliced shallots with the flour and salt. Shake off the excess flour. Heat a thin layer of neutral oil in a small pan over medium heat. Fry the shallots in batches for 2 to 4 minutes, stirring often, until golden and crisp. Transfer to paper towels or a rack and season lightly while hot. Pull the shallots when they are golden, not dark brown. They continue to darken after leaving the oil. That residual carryover colour development is exactly why pulling at golden, rather than waiting for a deeper brown in the pan, protects the shallots from tipping into bitterness by the time they've fully cooled.

Heat a heavy skillet or grill pan over high heat until very hot. Add the neutral oil. Sear the steak for about 2 to 4 minutes per side, depending on thickness, until deeply browned outside. Add the butter, garlic, and rosemary or thyme if using. Baste the steak for the final 30 to 60 seconds. For doneness, aim for rare at 49–51°C, medium-rare at 52–54°C, or medium at 57–60°C. Medium-rare is the best target here. Steak for salad should stay juicy and pink, not grey and dry. That final basting stage, added only once real colour is already established, layers in real, aromatic flavour from the butter, garlic, and herbs without needing to extend the steak's overall time on the heat.

Transfer the steak to a board and rest for 8 to 10 minutes. Slice across the grain into thin strips. Do not slice immediately. If you cut hot steak straight from the pan, the juices run out and the salad gets watery. During cooking, the steak's internal juices are pushed toward the centre under real pressure, and that rest period lets them redistribute evenly back through the meat rather than spilling out onto the salad the moment a knife cuts in too soon.

Wash and dry the greens very thoroughly. Place them in a large bowl with the cherry tomatoes and red onion. Add just enough vinaigrette to lightly coat the leaves and toss gently. The greens should look glossy, not wet. Too much dressing collapses the salad before the warm steak even goes on. Any residual surface water on the greens would dilute the vinaigrette on contact and prevent it from actually clinging, which is exactly why thorough drying matters here as much as it does for the dressing's own careful, light application.

Divide the dressed greens among 4 bowls or plates. Fan the sliced steak over the top. Add the blue cheese crumbles, crispy fried shallots, extra black pepper, and a small pinch of flaky salt. Drizzle with a little more vinaigrette if needed. Adding the blue cheese as distinct crumbles, rather than melting it into the dressing, keeps its own sharp, assertive character present as a genuinely separate component rather than diffused throughout the whole salad.

Serve immediately while the steak is still warm and the greens are still crisp. This salad's whole appeal depends on that direct contrast between warm, juicy steak and cold, crisp greens — any real delay lets both drift toward the same temperature, losing exactly the distinction the dish is built around.