“Jaccard” sirloins by poking many times on both sides with a fork (or use a jaccard tenderizer if you have one)
Place steaks into a bag or container with soy sauce and 15g of worcestershire, making sure to coat well and refrigerate for 15-20min.
Dry beef well with towels before searing.
Add a long glug of oil to pre heated heavy bottomed pot (over high heat) and carefully lay in steaks, making sure to press down on each for several seconds. Cook steaks on side 1 for about 90 seconds or until nicely browned. Flip to side 2 and cook for another 2-3 minutes.
Transfer steaks to a plate to rest. Temp should read about 128-130F/53-55C.
Add another squeeze of oil into the steak pot. Add mushrooms and pinch of salt, using a wooden spoon to scrape up beef fond. Saute for 4-5 minutes or until mushrooms have released some moisture, and most of the beef fond is scraped up.
Add chopped onion and another pinch of salt. Stir and continue to saute for 3-4min, stirring every minute and continuing to scrape up fond on the bottom of the pan.
Add garlic and cook for 10-15 seconds, then add wine. Stir to deglaze bottom of the pan. After about a minute or when wine has reduced, add tomato paste and flour. Stir. After about a minute of frying, flour and tomato paste should have glazed the bottom of the pot.
Add beef broth. Stir to work up glaze from bottom of the pot and bring to a simmer. Stir in mustard, worcestershire, and black pepper. Reduce heat to low and simmer for 10 minutes, covered.
When ready, the sauce should be thickened and glossy. Stir in heavy cream.
Add pasta to a pot of boiling, well salted water. Stir and cook per package instructions (8-9min).
When cooked to al denta, drain pasta, leaving about 1/4c of pasta water in the pot with the noodles. Add butter to the noodles and stir to emulsify as it melts.