Instructions
1Season: Pat beef dry. Toss with garlic salt, pepper, and flour.
2Sear: Heat 2 tbsp olive oil in skillet over medium-high. Sear beef in batches ~45 sec/side. Add oil between batches.
3Deglaze: Reduce heat to medium. Add 1 tbsp butter and white wine; scrape up the browned bits. Add onion; cook 4 min. Add garlic; cook 1 min. Off heat.
4Slow cooker: Add beef broth, bouillon, vinegar, Worcestershire, and Dijon; stir. Add seared beef + drippings, then onion mixture.
5Cook: 4-5 hr on high or 8-9 hr on low.
6Thicken: Whisk slurry into the slow cooker. Switch to warm.
7Yogurt finish: Whisk Greek yogurt with 1 cup of liquid from slow cooker until smooth (prevents curdling). Stir gently back in.
8Butter swirl: Heat off. Swirl in remaining 2 tbsp cold butter for a velvety finish.
9Serve: Cook egg noodles per package; serve stroganoff over noodles. Top with parsley.