Preheat oven to 375°F. Toss Bison meat with flour and salt in pepper. In a large Dutch oven or heavy-bottom pot over medium-high heat, add Olive Oil and brown the bison stew meat in batches until nicely seared. Remove and set aside.
In the same pot, add onion, carrots, and celery. Cook 5–7 minutes until softened. Add garlic and tomato paste and cook another 1–2 minutes, stirring until fragrant and slightly caramelized.
Pour in the red wine, scraping up any browned bits from the bottom of the pot. Let simmer 2–3 minutes to cook off the alcohol.
Return the bison to the pot. Add potatoes, thyme, bay leaves, and enough broth to just cover the mixture. Bring to a gentle simmer, cover, and cook for 40–50 minutes, until the bison is tender and potatoes are cooked through.
In a small bowl, whisk cornstarch with cold water to create a slurry. Stir into the pot and simmer 2–3 minutes until thickened. Remove bay leaves and adjust seasoning. Stir in frozen peas.
Transfer filling to a pie dish or baking dish. Top with pie crust or puff pastry, trimming edges and cutting small slits for steam.
Bake uncovered for 30–35 minutes, or until the crust is golden brown and the filling is bubbling. Let rest 10 minutes before serving.
