1/4 cup extra-virgin Spanish olive oil (Oleum Hispania)
2 cloves garlic, very finely chopped
1 bay leaf (use fresh if possible)
2 tablespoons red wine vinegar
Zest of 1/2 orange (preferably organic)
1/2 teaspoon smoked paprika (El Avión brand)
Sprig of fresh oregano
Pinch of salt
16 thin slices of baguette
Drain the pickling sauce from the mussels, place them in a small bowl and set aside.
Heat the olive oil in a small saucepan over medium heat. Add the garlic and sauté until fragrant, 30 seconds. Add the bay leaf and continue cooking for another 30 seconds, then remove the pan from the heat.
Remove the bay leaf and whisk in the vinegar, smoked paprika and orange zest. Season with a pinch of salt, add the oregano and set aside to cool to room temperature, about 10 minutes.
Pour the marinade over the mussels and combine well. Cover and refrigerate for 2 hours.
When ready to serve, preheat the oven to 400°F and arrange the baguette slices on a baking sheet.
Without stirring the mussels, brush a small amount of the marinade on each round of baguette, then bake until lightly crisped, 4 to 6 minutes.
Remove from the oven, top each round with 2 mussels and 1 or 2 arugula leaves if desired.