Trim the fish loin of any excess blood line. Combine the remaining ingredients and mix well. Rub the mixture over the char, wrap tightly in plastic and chill for 2 hours. Remove from the plastic and rinse well. Allow to air dry on a rack in the cooler for 1-2 hours.
Make the vinaigrette by simple combining the first 7 ingredients in a bowl and whisking vigorously to emulsify. Now season to taste with salt and fresh cracked pepper to taste. In a small saucepan, bring the syrup to a boil for 2 minutes. Remove from heat, allow to cool slightly and add the espelette and lemon zest. Let rest at room temperature.
Torch the outer edges of the cured fish to give it a slight char. Slice thinly, ¼”.
Dress the plate with a thin line of gastrique from end to end. Divide the fish slices evenly among 6 plates, centered over the gastrique. Last minute, dress the vegetables with the vinaigrette in a salad bowl. Adjust seasoning. Plate the salad centered lengthwise over the char. Serve immediately.