Baked Cod with ras el hanout onion jam from The Hog Island Book of Fish & Seafood: Culinary Treasure

Ingredients

• ¼ teaspoon freshly ground pepper
• 2 tablespoons olive oil
• 1 tablespoon apple cider vinegar
• 1 tablespoon fresh lemon juice
• Four 6-ounce (170-g) skinless cod or other white fish fillets
• ½ teaspoon ras el hanout
• Fine sea salt
• 2 tablespoons packed light brown sugar
• 1 teaspoon fine sea salt
• Chopped fresh flat-leaf parsley leaves, for garnish
• 2 large yellow onions, diced
• 1 teaspoon ras el hanout
• Lemon wedges, for serving