Preheat barbecue to medium high heat.

Place cut zucchini and squash, in a colander and sprinkle with sea salt. Allow to sit and “sweat” out some of the natural moisture for 5-10 minutes, and then blot with a paper towel.

Mix oil, vinegar, mustard, and syrup in small bowl. Place zucchini, squash, onion, and mushrooms in large bowl and pour in oil and vinegar mixture, mixing well so vegetables are coated.

Place vegetables on grill matt on barbecue, and cook about 8-10 minutes, tossing occasionally.

Remove from grill, place in bowl, and cover tightly with aluminum foil. Let sit 5 minutes and then serve. (Can double this recipe and keep uneaten vegetables in refrigerator for up to 5 days)