Place all ingredients in large freezer bag. Mix gently to combine. Remove excess air, seal and freeze.
Thaw. Slow cooker on low for 6-8 hours.
Instant Pot: Manual pressure on high for 50 minutes, natural release. Shred. Serve over rice.
A 2 lb. roast is on the smaller side but if you end up using a larger roast and cooking it in the instant pot, we recommend slicing your roast into 3-4 equal sized chunks before adding it to your bag. It will cook more evenly and shred more easily.