Bring the already-cooked fresh tagliatelle up to temperature: place the 1 cup (140 g) of cooked tagliatelle in a colander and pour a small amount of boiling water over it (or microwave 30–45 seconds). This loosens the noodles so they separate easily and take the sauce better — set aside in a warm bowl while you finish the sauce.

Pat the beef dry with paper towels and season lightly with salt and a generous grind of black pepper. Drying the beef removes surface moisture so it sears instead of steams; good seasoning at the start builds the foundation of flavor.

Heat a heavy skillet (cast-iron or stainless) over medium-high heat until hot. Add 1 tbsp olive oil and let it shimmer. High heat gives the beef a quick caramelized crust (Maillard reaction) that adds savory depth — don’t overcrowd the pan or the meat will steam instead of browning.

Add the beef in a single layer and sear for 45–60 seconds per side, just until browned but still glossy (thin slices cook very fast). Remove the beef to a plate and loosely tent with foil. Quick searing locks in juices and creates intense flavor; removing it prevents overcooking while you make the sauce.

Reduce the heat to medium. Add the sliced cremini mushrooms to the same skillet and season lightly with salt. Let them cook undisturbed for 2–3 minutes so their water evaporates and they brown. Browning concentrates the mushroom flavor and creates fond (brown bits) that will enrich the sauce.

Stir the minced garlic into the mushrooms and cook for 20–30 seconds until fragrant — garlic burns quickly, so add it only after the mushrooms have started to brown to avoid bitterness.

Turn the heat to low. Return the beef and any accumulated juices to the skillet. Add 2 tbsp crema (or sour cream) and 1/2 tsp Worcestershire sauce. Gently fold to combine and warm through — do not boil. Cooking the crema gently creates a silky emulsion without breaking (curdling); Worcestershire adds umami and a faint tang to balance the cream.

Taste and adjust seasoning with salt and black pepper. Stir in the torn fresh basil off the heat — heat dulls fresh herbs, so adding basil at the end preserves its bright aroma and color.

Add the warmed tagliatelle to the pan and toss gently to coat in the sauce, letting the pasta pick up the beef-mushroom pan juices for 30–60 seconds. If the sauce feels too thick, add a tablespoon of reserved pasta cooking water (or warm water) to loosen — the pasta water’s starch helps the sauce cling to the noodles.

Serve immediately on a warmed plate: twirl the tagliatelle into a nest, top with the beef and mushrooms, and finish with an extra crack of black pepper and a few basil leaves. Serve hot — stroganoff is best right away when the sauce is silky and the beef tender.