Prepare Freezer Bags: Add ingredients directly to freezer bag and separate storage bags (no mixing required!) and freeze until you’re ready to cook. Be sure to freeze the main ingredients in a large freezer bag and the vegetables in separate small storage bags.
To Cook: Determine the appliance you will use to cook this recipe and, once decided, follow the “Instant Pot Instructions” or “Slow Cooker Instructions” as written below.
Instant Pot Instructions: Add frozen ingredients to your Instant Pot insert, set Instant Pot to “Manual” and set the timer for 110 minutes. After cooking, allow the Instant Pot to naturally release pressure. Once you can unscrew the lid of the Instant Pot, it’s fully depressurized. Add in radishes and celery, screw lid back on, and set Instant Pot to “Manual” for additional 1 minute. After cooking, manually depressurize (“quick release”) Instant Pot by opening steaming valve before removing the lid. Move on to “Final Steps” as written below.
Slow Cooker Instructions: Thaw ingredients in the refrigerator (this may take upwards of 1 day). Add thawed ingredients from large freezer bag to your slow cooker, set to cook for 8 hours on low. Stir in radishes and celery to slow cooker with 2 hours remaining. Move on to “Final Steps” as written below.
Final Steps: Using tongs, transfer meat from Instant Pot to bowl. Using forks, shred meat before returning shredded meat back to Instant Pot. Serve pot roast in bowls and garnish with fresh thyme.