In a large microwave safe measuring cup or bowl use a fork and stir together the vinegar, brown Swerve, ketchup and soy sauce until smooth
Microwave on high for 30 seconds. Use fork and stir. Microwave on high another 30 seconds or until hot
Use fork and stir sprinkle in xanthan gum and stir until fully combined
Microwave on high another 30 seconds. Stir. Keep microwaving in 30 second intervals until the sauce has thickened. This should only take about 1-1 1/2 minutes total. Allow to cool then serve