Both potatoes and sweet potatoes should not be baked together since they cooked at a slight different temperature and time.
Secondly to attain the ultimate crunchiness they should not be jumbled upon in a pile like pictured above.
They should be a wee space in between.
I was fortunate that all the men in the house did not care about this. Not crunchy and overcooked sweet potatoes. The more the better.
I have acquired a recipe for deep frying/oven baked sweet potatoes/potatoes.
HOW TO DEEP-FRY CRUNCHY FRIES (or OVEN-BAKED FRIES)
1) Acquire potatoes/sweet potatoes
2) Slice as you would call fries.
3) Soak it in water for about 30 minutes
4) Pat dry
5) Toss in cornstarch. Easy way to do it is to place a tablespoon of the cornstarch in a container (or non-sticky plastic bag), pour the potatoes in (they should be dry by now), close the lid and shake it like a Polaroid picture! The flour should coat it nicely and a thin layer will do.
6) Coat it with olive oil or any vegetable oil. Use your hands for better oil distribution.
7) Deep-fry in very hot oil/Bake in oven at about 200-220 degrees for about 15 minutes for sweet potatoes and 25-30 minutes for potatoes.
Guaranteed hit! Got this recipe from a Potato Pro.