Brown the steak bites. Melt 1 tablespoon of vegan butter in a large deep skillet over medium heat. Add the vegan steak bites and cook for 5 minutes, turning frequently until browned on all sides. Remove from the skillet and set aside. Do not wipe out the skillet — those browned bits add flavor to the gravy.
Add the remaining tablespoon of vegan butter to the skillet. When melted, add the chopped onion and cook for 3 minutes until softened.
Stir in the flour and cook for 2 minutes, then add the garlic and cook for 1 minute more. Cooking the flour first removes the raw taste and gives the gravy a rich, smooth consistency.
Whisk in the beef-style broth, Worcestershire sauce, and tamari until smooth.
Return the steak bites to the skillet and stir to coat. Bring to a boil, then reduce to a simmer. Cover with the lid slightly ajar and simmer for 30 minutes, stirring every 5 minutes, until the gravy is rich and thick.
Serve hot over mashed potatoes, rice, or pasta.