If using wooden skewers, soak eight in water for 15-30 minutes.
Preheat your grill to medium high.
Cut ends off zucchini. Using a vegetable peeler or mandolin, carefully slice lengthwise until you have several zucchini ribbons. Lay onto paper towel lined baking sheet and salt each piece well. Set aside letting them sit for at least 30 minutes turning occasionally. Wipe off excess water and salt.
Brush grill with olive oil, and then grill the sausages until partially cooked, about 7 minutes, rotating while cooking. Remove from heat, tent and set aside to cool.
Slice onion in half lengthwise and into four wedges. Cut the wedges in half crosswise if the onion is large and into smaller chunks roughly the same size as the other pieces going onto your skewer.
Slice the cooled sausage into chunks about the same size as some of our skewered vegetables for even cooking.
Whisk together olive oil, white wine vinegar, za'atar spice and a good pinch of salt and pepper.
Alternate sausage with zucchini and onion on your skewers. Brush skewers with olive oil mixture and grill, turning every couple of minutes. Do this for another 7-10 minutes, brushing with olive oil until all used, to ensure your sausages are cooked through.
Remove from grill and serve.