Heat the remaining oil in the sauté pan on medium heat. Add the onions and cook until they become translucent, about 3 minutes. Add the bison, garlic, salt, black pepper and rosemary and mix. Cook the bison until it browns, about 5 minutes. Add 2 teaspoons of butter and the remaining tablespoon of flour, stirring to incorporate, for 2 minutes. Once flour is incorporated and slightly cooked, mix in the beef stock and carrots. Let simmer on medium heat for 5 minutes. Mix in the peas and corn. Cook 5 more minutes, stirring often so the mixture doesn’t burn. Set aside.