Steps

1. In a bowl, whisk together the vinegar, lemon juice, shallots, garlic, parsley, salt and pepper. Still whisking, slowly pour in the olive oil to combine. Adjust seasoning.
2. In another bowl, toss the trout, arugula and sliced potatoes with some of the champagne vinaigrette. Place on individual plates or in a serving bowl and served any extra vinaigrette on the side.