Preheat Oven:
If using an oven, preheat to 350°F (175°C).Brown Beef Chunks:
Heat oil in a large skillet over medium-high heat (or in a large oven-safe pot like a Dutch oven). Brown beef chunks on all sides for a few minutes, seasoning with salt and pepper. Transfer to a 5-6 quart slow cooker (or set aside on a plate).Sauté Aromatics:
Add onion and garlic to the pan; cook for 2 minutes. Stir in Italian seasoning and tomato paste, then add 1/2 cup beef broth and soy sauce. Deglaze the pan by scraping up browned bits, then pour mixture into the slow cooker (or return meat to the Dutch oven).Add Vegetables and Broth:
Add all vegetables except peas, then pour the remaining 2 cups of broth over the top.Slow Cook Stew:
Cook on LOW for 6-8 hours or on HIGH for 3-4 hours. (For oven method: cook for 2 hours, stirring carefully every 30 minutes; reduce heat to 320°F (160°C) if top ingredients brown too quickly. Do not stir if using a slow cooker.)Add Peas:
Remove lid, stir, and add peas. Cook uncovered for 15 more minutes (or 5 minutes on stovetop).Thicken with Glucomannan:
To thicken, mix glucomannan with a few tablespoons of cold water in a small bowl. Add one-third of the mixture to the stew, stirring well. Wait 1-3 minutes for thickening to occur. Repeat as needed until desired consistency is reached. Serve immediately.