Add 1 tablespoon olive oil to base of slow cooker and place over medium high heat. Add beef, season with salt and pepper and brown in batches, so that you give the meat room for a nice sear. This should take about 5 minute per batch of meat.
Next add in beef broth, dry red wine, tomato paste, soy sauce, balsamic vinegar, thyme and salt and pepper. Stir together with the beef until combined, then add in garlic, onion chunks, carrots and diced potatoes. Add more broth as needed so ingredients are covered by liquid.
Cover and cook on low for 7-8 hours or on high for 4-5 hours. I prefer to cook this slow and low so that the beef become really tender and the flavors have time to meld together.
Next, remove 1 cup of beef broth from the slow cooker and transfer to a medium bowl. Whisk in ¼ cup flour until there aren’t any lumps remaining. Add back to the slow cooker and stir to combine. Add in frozen peas and cook uncovered on HIGH for 10-15 more minutes until beef stew thickens up a bit.