Blanch them, dry them, give them a good coat of oil, then put them on 1/2 sheet pans in a 450 oven. Rotate, flip, shake, etc. Remember the salt. They will come out OK, but still not like actually frying them.
Speaking of frying.......what's the beeb's consensus on air fryers. My one buddy swears by his. I've heard everything from they are greater than sliced bread to they are a redundant toaster oven?
When I grill, my wife will often make some steak fries in the oven. She uses olive oil and some other stuff. Pretty tasty!!!
I've got a t-fal actifry. It's great for making fries, and we probably use it once a week. If you've got a convection oven it's pretty much the same thing so don't waste your money.