Metal or wood skewers (if using wood, soak in water for at least 30 minutes to prevent burning)
Salt and pepper to taste
2 tablespoons cooking oil
Thaw salmon if frozen. Rinse salmon and pat dry with paper towels, cut crossway into ½-inch wide strips and place in large ziplock bag. Add vinegar, lemon juice and zest, and fresh dill to bag. Seal tightly and shake to combine. Marinade in refrigerator for 30 minutes at most (do not marinade longer or the vinegar will start to cook the salmon).
Preheat gas or charcoal grill to medium heat. Remove salmon from bag and discard marinate. Thread salmon pieces accordion-style (see pictures above for reference) onto skewers, alternating with zucchini slices. Sprinkle with salt and pepper.
Wet a paper towel with cooking oil and rub onto grill to prevent sticking. Immediately place skewers on grill. Cook uncovered for 6-10, rotating every few minutes, until grill marks appear and fish is flaky when tested with a fork.
Optional: squeeze more lemon juice on top when serving.