Wine steamed mussels

For ➍
2 tbs butter
1 tbs olive oil
1 tbs onions, finely chopped
1 tbs celery, finely chopped
1 tbs carrots, finely chopped
2 medium shallots, sliced thinly
1 clove garlic, crushed and chopped
1½ ts teaspoons fresh, chopped thyme
1½ ts fresh, chopped parsley
1½ ts fresh, chopped sage
½ ts salt
¼ ts ground black pepper
50 cl dry white wine
1 kg mussels, cleaned*

In a large skillet, over medium heat, melt the butter and olive oil and sauté the onions, carrots, celery, shallots, and garlic until they are just tender, about 5 m. Add the thyme, parsley, sage, salt, and pepper to the vegetables and cook for 1 m. Add the white wine to the skillet and bring it to a gently simmer. Add the mussels to the wine sauce, turn the heat up a bit, cover, and steam the mussels for 5 m, or until the mussels open. Serve the mussels hot with the wine sauce.
Serve with frites or slices of baguette bread.

*For a Belgian main dish, 1 kg mussels per person would be expected. Use several skillets to cook them in. Fill the skillets for ⅔, leaving room for the mussels to open their shells.