Roast Beef Sandwich Spread

I've put off posting this recipe because I knew the picture wouldn't be pretty.  This is not a pretty dish, but it's delicious and a great way to use leftover roast beef. It's comfort food, I guess, for me because my mother used to make it as we'd eat roast beef nearly every Sunday for dinner.  Then we'd have these sandwiches that evening.

Roast Beef Sandwich Spread
In a food processor or really good blender, layer the following (If you're using a blender, it's best to put the liquid ingredients in first ):
Start with about 1/4 cup to  1/2 cup dill pickle juice
About 1/2 cup mayonaise
A couple of good squirts of mustard
Leftover roast beef
You can also add dill pickle and/ or onion

Pulse or blend until the desired consistency.  Serve on bread and top with tomato and lettuce.