Rinse the mussels under cold running water, scrubbing the shells with your hands or a small brush to remove any debris. If any mussels are open, give them a gentle tap on the counter and discard any that do not close. Remove the beards by gripping the fibrous threads with your fingers and pulling firmly toward the hinge end of the shell.
Melt the butter in a Dutch oven over medium-low heat, add the minced garlic, and cook until fragrant, about 1 minute, being careful not to brown it.
Stir in the white wine, Dijon mustard, and bay leaf, then simmer at a lively bubble for 1 to 2 minutes.
Add the mussels to the pot, place the lid on snugly, and steam for 7 to 10 minutes, shaking the pot once halfway through, until the mussels have opened.
Use a slotted spoon or tongs to transfer the mussels to a large bowl, discarding any that have not opened.
Strain the cooking liquid through a fine mesh sieve set directly over the mussels to remove any grit or sand, then scoop any strained garlic solids in the sieve back over the mussels. Season with freshly cracked black pepper to taste and serve immediately with sourdough bread for dipping.
Notes
For detailed ingredient notes, substitution tips, variations, and step-by-step photos, scroll through the full recipe post.
Use a digital kitchen scale for precise measurements and an oven thermometer to confirm your oven is heating correctly.
To switch to gram measurements, click "Metric grams" in the ingredients section of the recipe card.
Discard any mussels with cracked shells before they go into the pot.
Pull the beards toward the hinge end of the shell, and they should come off cleanly.
Start checking for open shells at the 7-minute mark so the mussels don’t overcook.
Storage
Store leftover mussels and broth in an airtight container in the refrigerator for up to 2 days.
If you prefer, remove the mussels from the shells and store them directly in the broth to save space and make reheating easier.
Warm gently on the stovetop until heated through, as boiling can make the mussels tough.