Grilled Vegetable Platter

2 lb. yams, peeled and diced

2 lb. med. red potatoes, sliced ¼-in. thick

2 lb. portobello mushrooms

2 lb. asparagus, ends trimmed

2 lb. green bell peppers, bottoms removed and thick slices cut from each side

2 lb. yellow bell peppers, bottoms removed and thick slices cut from each side

2 lb. red bell peppers, bottoms removed and thick slices cut from each side

2 lb. zucchini, sliced ¼-in. thick on bias

2 lb. yellow squash, sliced ¼-in. thick on bias

Olive oil, as needed

Salt and pepper, to taste

1 jar (14 oz.) grilled artichokes, drained (reserve liquid)

1 jar (12 oz.) gherkins, drained

1 jar (12 oz.) pepperoncini, drained

1 jar (10 oz.) roasted tomatoes, drained (reserve liquid)