The first step is sourcing good mussels. If you can go to a fish market, that is the best, but high-end organic grocery stores also have great shellfish. Look for ones that are closed tight and smell fresh, like the ocean.
Clean them by pulling the beard away and scrub with a hard brush.
Set a large sauce pan on medium heat and bring to a simmer: white wine, Dijon mustard, garlic, butter, saffron, salt and freshly ground pepper.
Add 2 lbs of cold, live mussels, increase heat and cover tightly with lid.
Steam for 5 minutes, just until all mussels are open. Remove from heat and discard any mussels that didn't open.
Divide mussels and broth into 2 bowls, top with freshly chopped parsley and serve immediately with double-fried potatoes, crusty bread or your favorite potato chips.