In a small bowl, combine the kosher salt, basil, oregano, and garlic powder.
Unwrap the roast and sprinkle on all sides with the herb mixture. Place the roast and beef broth in a slow cooker.
Set to low and cook for 3–4 hours on high or 4–6 hours on low. (I have a newer slow cooker, which cooks things quickly. Mine was done after 4 hours on low.)
Meanwhile, seed the peppers. Cut each pepper into 6–8 slices vertically. 30 minutes before the roast is done, add the sliced bell peppers to the slow cooker.
Remove the roast. Leave the bell peppers in the slow cooker and set the slow cooker to warm.
Let the roast cool for 30 minutes, then slice the roast into ⅛ inch thin slices, or however thin you can cut it with a sharp knife.
When ready to serve, remove the green bell peppers from the slow cooker. Strain the liquid into a bowl. Divide the liquid among ramekins or small dishes for dipping the sandwiches.
Divide the beef evenly among the French rolls. Pour a tablespoon of the liquid (au jus) on top of each of the beef sandwiches.
Top with either the green bell peppers (if you prefer it sweet) or the giardiniera (if you prefer it spicy). Serve immediately with extra au jus for dipping.