In a small bowl, whisk together the white wine vinegar, whole grain mustard, minced garlic, olive oil, kosher salt, and black pepper until combined.

Use a vegetable peeler or mandolin to thinly slice the zucchini into long ribbons.

In a large bowl, toss the sliced zucchini with about half of the vinaigrette.

Stir in the toasted pine nuts, crumbled feta cheese, and minced chives. Drizzle more vinaigrette over the salad as desired.