So. Twenty four hours before you want to eat, you need: A paring knife, a cutting board, a crock pot, a splash of olive oil, some salt and pepper, a 2lb slab-o-beef, and about a third of a 24oz jar of pepperoncini. What you're looking for in that slab-o-beef is nice marbling. I've used chuck with great success. What you're looking for is something that can cover the bottom of your crock, about an inch or so thick.
Crock pot on low, splash the oil. Rinse the slab and pat dry with paper towels. Salt it generously on both sides and into the crock pot. Grind some pepper on top. You want maybe 8 ounces of pepperoncini juice in the crock pot. Now, stem and seed all the pepperoncini that are above the juice line. I stem, slice the remainder in half and use my thumb. Toss the halves into the crock pot.
Wash your hands! Particularly before you touch your eyes or visit the bathroom for purposes other than washing your hands. Don't say I didn't warn you... Put the jar of pepperoncini in the fridge, cover the crock pot and walk away.
The next day, get a nice loaf of ciabatta bread or some crusty french loaf and make some sandwiches. A little sharp cheddar is nice. Some Parmigiano Reggiano is nicer still.
A sprinkle of rosmarino (or a sprig) wouldn't be the end of the world. Neither would increasing the amount of pepperoncini or being less aggressive about seeding them. Sorry, no pitcure. It hardly ever lasts long enough...
Credit has to go to Michele Martin of PA for this one. Michele, let me say, "Thank you!" for everyone...