Preheat oven to 350F.
Heat 1 tablespoon butter in a large, heavy bottom saucepan over medium heat. Add the onion and salt and cook, stirring often, until softened, about 5 minutes.
Add the wild rice blend and saute, stirring constantly, for about 2 minutes.
Add 4 cups of the hot vegetable broth to the rice and onion mixture and bring to a boil.
Cover the pot with a tight lid and place in the oven for 20 minutes.