Drizzle olive oil on zucchini, squash, mushrooms, peppers, asparagus, and onion; season with salt & pepper. Grill on med-high heat until tender and skins on peppers are blackened. Cover and allow to cool.
Pour boiling water over couscous, cover.
Make dressing: combine lemon juice and herbs; whisk in olive oil.
Remove skins from peppers, chop. Chop remaining vegetables into bite size pieces.
Fluff couscous, add vegetables, dressing, and olives, and stir to combine. Keep cool until serving.