Once you have made your roast "beef", let it cool and it will firm up as it cools.
While the roast "beef" cools, make the sauces. Make the red ranch first. Add the ketchup, apple cider vinegar, agave, garlic, onion, salt and pepper to a small mixing bowl. Whisk to combine. Set aside.
Make the vegan cheddar sauce. Heat the vegan butter on medium high in a medium sized sauce pan.
Once the butter has melted, add the flour and whisk to combine, making a roux.
Let the roux simmer for a minute, then pour in the non-dairy milk and a pinch of salt and pepper. Whisk to combine, making sure there are no lumps of roux left.
Bring to a simmer and then reduce heat to medium low, let simmer, whisking constantly until the mixture thickens. About 2 to 3 minutes.
Add the vegan cheddar and continue whisking until the cheese has melted and the sauce is smooth. Taste and add more salt and pepper if needed.
Slice the roast "beef" very thin. Then put together your sandwiches. Spread a little bit of the red ranch on the top and bottom of an onion roll, then lay as many sliced of the roast "beef" as you want on to the roll. Then drizzle with the cheese sauce. Then serve. This recipe makes a lot, you should be able to make at least 8 sandwiches.