Steak Salad with Roasted Tomatoes and Tarragon Dressing

Tomatoes: buy for sweetness, not size — small vine or plum tomatoes halved are more reliable here than big beef tomatoes, which carry more water relative to flesh and take longer to concentrate. If tomatoes are genuinely poor — midwinter, no flavour — a tin of good plum tomatoes halved and roasted will actually beat a bad fresh one; you're chasing sugar and structure, not the word "fresh."

Tarragon is the one herb in this dish doing a job nothing else quite does — it has an aniseed note that cuts through the richness of crème fraîche and butter the way parsley or basil simply can't. If you can't get it, chervil is the closest relative in flavour family; failing that, a small amount of fennel frond will give you the aniseed note without pretending to be tarragon. Don't reach for dried tarragon in the dressing — dried herbs in a cold, uncooked sauce taste of paper, because they need heat and time to rehydrate and release anything.

The dressing itself — crème fraîche plus a little mayonnaise — is really asking: how much fat with how much tang? Crème fraîche alone can be slightly thin and sharp; the mayonnaise rounds it out and gives it a cling that plain soured cream won't. If you've only got soured cream, use it, but expect a thinner, sharper result and maybe ease back on the lemon juice. Mustard here isn't for heat, it's an emulsifier and a flavour anchor — English mustard will push the dressing towards sharp and hot, Dijon keeps it rounder; either works, just know which effect you're choosing.

The steak cut matters less than people think for a salad like this, because it's sliced thin after resting rather than served whole — a sirloin or rump will do the job at a fraction of the cost of fillet, since you're not relying on the steak alone to carry the plate. Use any oil with no smell of its own if you're topping up the butter in the pan — a neutral vegetable or rapeseed oil, never olive oil for the sear itself, because its flavour fights the butter and its lower smoke point means it catches before the meat's crust has formed. Butter is there for two reasons: the milk solids in it brown and add a nutty note the meat alone won't give you, and butter at a UK hob's "as hot as it'll get" setting is genuinely close to ideal for a steak this thin — you don't need the ferocity of a kazan fire here, a heavy frying pan on your highest ring does the job, you're just watching the foam go from bubbling to just turning gold-brown as your cue to add the meat.

Avocado and cucumber are there for cool, wet crunch against the warm roasted tomato and hot meat — not for their own flavour, which is mild to the point of being furniture. Any ripe, unbruised avocado works; if avocados are out of your budget or your fruit bowl, a few slices of fennel or even extra cucumber will do the textural job, just without the creaminess avocado brings against the tang of the dressing.

One honest limit of the ordinary flat kitchen: you won't get the tomatoes blistering and slightly charred the way a very hot commercial oven or an open flame would give you — your fan oven at 200°C will get you soft and sweet, not smoky, and that's fine. Don't chase char you don't have the equipment for; roasted-soft is the dish this recipe is built around, not roasted-charred. And this is a dish where patience is genuinely an ingredient — rush the resting of the meat, skip the rest on the dressing, and you haven't ruined it, but you've made a lesser version of the same thing, which is its own quiet kind of waste.