In a medium saucepan over medium heat, melt butter. Saute onion and carrot until softened but not browned (about 6 minutes). Add rice, stock, salt, and pepper. Stir to combine. Cover and cook over low to medium heat until liquid is absorbed (about 25 minutes). Serve warm.
Multigrain Pilaf: Use 1 cup long-grain white rice; 1 cup wheat berries, rye berries, triticale berries, or barley; and 1/2 cup wild rice. Increase chicken stock to 5 cups. Cook pilaf for 40 minutes.