Preheat oven to 400 degrees Fahrenheit (200 degrees Celsius).
Toss bell peppers, zucchini, and red onion with olive oil and salt on a large baking sheet; roast for 20 to 25 minutes until tender and slightly charred.
Season steak strips with salt and press the crushed peppercorns into the meat to adhere.
Heat butter in a large skillet over medium-high heat. Sear steak strips for 2 to 3 minutes per side until browned; remove from skillet and set aside.
In the same skillet, sauté shallots and garlic for 1 minute until fragrant.
Deglaze the pan with brandy, scraping up browned bits, and simmer until liquid is reduced by half.
Stir in beef stock and heavy cream; simmer for 5 minutes until the sauce thickens and coats the back of a spoon.
Return steak and any accumulated juices to the skillet and toss to coat in the sauce.
Serve the creamy pepper steak immediately alongside the roasted vegetables.