Feel free to substitute vegetables according to what you have on hand.
In a bowl combine 2 teaspoons coarse salt, pepper, and oregano; set aside.
Place sliced eggplant in a colander, and sprinkle both sides with remaining 2 teaspoons salt. Let sit 1 hour. Rinse quickly, and pat dry with paper towels; set aside.
Heat a grill or grill pan over medium-high heat. Arrange eggplant, peppers, zucchini, squash, radicchio, endive, and onion on a large rimmed baking sheet. Brush with the olive oil; sprinkle with salt-oregano mixture. Toss gently until evenly coated. Grill in batches until tender and grill marks appear (times will vary with each vegetable). Transfer back to baking sheet; let sit until cool enough to handle. Cut into 1-inch pieces, and transfer to a bowl. Add parsley and thyme, and toss to combine. Season with additional salt mixture if desired. Serve warm or at room temperature.