For the leeks:
For the champagne vinaigrette
For the leeks
Preheat the oven to 425°F. Cut the leeks in half lengthwise, then rinse and dry them well. Slice them lengthwise again into long, thin strips. In a mixing bowl, drizzle with a bit of olive oil and toss with the flour, paprika and garlic salt. Spread in an even layer on a baking sheet and bake, stirring once or twice, until the leeks are crispy and golden brown, 10 to 12 minutes. Remove from the oven and let stand until salad is assembled.
For the champagne vinaigrette
Whisk together the vinegar, garlic, mustard, and sugar in a small mixing bowl. Add the oil in a thin stream, whisking constantly, until emulsified. Season to taste with salt and pepper and set aside.
To assemble the salad, place Red RomaBlend, hazelnuts, and apples in a large salad bowl. Drizzle with the vinaigrette and toss to combine, adjusting dressing and seasoning as needed. Divide salad among six plates, and top with frizzled leeks and crumbled cheese.