Place the beef in a slow cooker and sprinkle with the entire pot roast seasoning packet.
1 Beef Tri Tip, 1 Packet Mrs Dash Pot Roast Seasoning
Add the butter on top, place the lid on and cook on low for 8 hours, flipping over halfway through and dumping the juices over the top to flavor the other side.
1 1/2 Tablespoons Butter
For the Onions
About 20 minutes before the beef is done, add the butter to a skillet and heat over medium heat until melted.
1 Tablespoon Butter
Add the onions, turn down to low and let the onions caramelize for about 20 minutes.
1 Onion
For the Gravy
Once the beef is done, scoop out 3/4 cup of the juices and place in a sauce pan over medium heat.
Add the water and bring to a boil, whisking to break up any browned bits.
1 Cup Water
In a small bowl combine the cold water and corn starch.
1/4 Cup Cold Water, 2 Tablespoons Cornstarch
Add 2 tablespoons of the hot liquid to the cornstarch mixture and then while whisking the drippings, slowly pour in the corn starch.
3/4 Cup Beef Drippings, Salt and Pepper
Whisk to combine, bring back to a boil and then turn down to a simmer for about 10 minutes or until thickened.
To Assemble
Cut the hoagie open and butter each side of the bread.
Hoagie Rolls, Butter
Heat the oven to broil and lay the bread open so it can get browned. DO NOT WALK AWAY! I know you think you can run to change the laundry but the bread will burn. Talking from experience here.
Remove the bread from the oven.
Using tongs pick up chunks of the meat, it should fall apart, no cutting needed. Place on the bread, top with gravy and caramelized onions.
Enjoy!
Notes
Depending on the size of your tri tip your meat could be done around 6-7 hours, just keep checking on it. We tend to buy bigger pieces at Costco so we are almost always 8 hours.left over pot roast will keep for 3-4 days in the refrigerator