Preheat the oven to 350.
Heat a grill pan or skillet over medium high heat. Once the pan is really hot, add the oil, then place the steak in the pan. Sprinkle salt and pepper on the steak. Sear 4-5 minutes on the first side until it has browned.
Flip the steak over and cook another 4-5 minutes on the second side. (The steak was medium-rare at this point, which I preferred since the steak was going to be cooked again once the dip was in the oven. But if you prefer, you can cook the steak longer to medium.)
Remove the steak from the pan and let rest 5-10 minutes before you cut it.
Saute the onion and bell pepper in the grill pan until tender, about 5 minutes.
Cut the steak against the grain into thin slices, then dice the steak slices.
In a medium baking dish, mix the cream cheese, mayonnaise and provolone together. Stir in the diced steak and sautéed onion mixture. Spread into an even layer and bake in the preheated oven for 20-25 minutes until the cheese is starting to brown on top.
Serve with toasted baguette or rolls.