Hoping to create a heartiest stew, I was thinking of roasting my carrots, okra, and sweet potatoes. Will it create any substantial change in flavor?
You will get the roasty, caramelized flavors; how much influence they will have on the overall flavor of your stew will depend on several factors including:
- How deeply you roast the them
- How much you add, proportionately, into the stew
- How strongly flavored the other items in the stew are
Roasting the vegetables will also cook them, so you will want to add them to the stew much later, so they don't overcook.
If you google roasted vegetable stew, you will find several recipes for inspiration.
As to whether this is a superior, or heartier flavor, that would be a matter of opinion. You don't mention roasting celery or onions (partners with carrots in the classic mire poix), but these are also excellent candidates for roasting, as are all types of root vegetable.