Pat beef dry with paper towels and season with salt and pepper. Heat oil and butter in a Dutch oven or large ovenproof pot over medium-high. Add beef and cook for 8 to 10 min, turning, until nicely browned. Remove beef from pan and drain all but 2 tbsp fat.
Add onions, carrot and celery, and sauté on medium for 5 min or until vegetables are browned. Add garlic and tomato paste and sauté 1 min longer.
Add wine and bring to a boil (scraping bottom of pan to incorporate any bits), for 2 min or until reduced by about 1/3.
Add passata and thyme, and bring mixture to a boil again.
Add beef, cover pot and place in the oven for 3 to 4 hrs (alternatively, transfer mixture to a slow cooker and cook on high for 4 to 5 hrs), turning meat occasionally, until beef can be easily pulled apart with a fork and sauce is thick. Remove meat and skim fat from sauce. Pull meat into pieces and return to sauce or reserve for Braised Beef Tacos. Serve ragout over pasta, use in Easy Braised Beef Lasagna or freeze for another day.