Unlike soup, you can't just add water to a side of roasted carrots. But you still have options.
The Quick Rinse
If the veggies are sturdy (like broccoli or potatoes), put them in a colander and rinse quickly with hot water. Dry them in a hot pan with a little unsalted butter to restore the texture.
The Grain Buffer
Serve the salty vegetables over a completely unsalted base like plain rice, quinoa, or mashed potatoes. The bland base will absorb the excess salt from the veggies as you eat.