In a large measuring cup or bowl, mix together broth, coconut aminos, sesame oil, and garlic.
Add sliced beef and bell peppers to lined slow-cooker, in liquid; toss to coat.
Cook on low 6-8 hours, or high 3-4 hours.
Once beef is tender and done cooking, in a small bowl or ramekin, whisk together arrowroot and cooking liquid until there are no lumps, pour into slow cooker and stir to mix well. Cook on low for an additional 30 minutes to thicken up the sauce.