Preheat the oven to 400 degrees Fahrenheit.

Grease a sheet pan with two to three tablespoons of olive oil. Spread out the cut leeks and dates and toss to coat with the oil. Sprinkle with salt, to taste. Place the pan in the oven and bake for about 10 minutes, stirring once after five minutes.

In a small bowl, combine the honey, parsley, garlic cubes, zest and half a teaspoon salt, and smear all over the salmon. When the leeks have softened, (after about 10 minutes) remove the sheet pan from the oven and make a space in the middle, and carefully place the salmon on the pan. Return the pan to the oven and cook for an additional 20 minutes.

Remove the pan from the oven and spoon the leek and date mixture onto the top of the fish.

Drizzle with lemon juice before serving if desired.