I always make a lot, and it's never, ever enough. Everyone loves these sandwiches. I use round roast because it holds together well after slow-cooking, making for nice sandwich slices. I usually cook the meat the day before serving, to allow it to cool for better slicing.
Heat olive oil in skillet; brown the roast on all sides. Place roast in large crock pot. In a small bowl, combine broth and remaining ingredients; stir well. Pour over roast; cook on HIGH for 5 hours or until tender (but not fall-apart tender).
Remove roast from crock pot, cover, and refrigerate. Strain broth into a storage container and keep refrigerated until ready to use.
Slice chilled meat very thinly and place into crock pot or large saucepan. Pour strained broth over meat, and cook gently until heated through.
Slice hoagie rolls in half, lengthwise. Butter, then place under broiler or on skillet until toasted.
Serve meat slices, piled high on toasted crusty rolls, with heated broth on the side, for dipping. Cheese slices and pickled peppers or vegetables are optional, but delicious.