I'm not certain where you're from and I don't wish to assume you're in the states so.......here in the states, close to 30 years ago, we had a concept off-shoot of TGI Friday's called Dalt's. They had a terrific fry recipe that was eventually adopted at Friday's. Unfortunately it was never produced properly. Dalt's went out of business and Friday's eventually dropped it going for the crappy frozen fry. Just know that, if you do the steps, the fries turn out amazing.
Cut fries 5/16" juliene into a sink full of water. agitate and drain water. Transfer fries to A-Lexans or a Brute food storage container on wheels. Salad keeper bottom drain bin works best because of the drain spigot on the bottom. Either container should be filled with water over night and be certain to cover potatoes completely with water or discoloring will take place. You'll also find the water has turned a reddish brown over night. This is normal also, the starch will have settled to the bottom in a milky-white appearance.
The next morning, heat fryers to 275 deg. While fryers are heating, drain off the amount of potatoes you'll be prepping for the shift or day. Fill baskets of fryer 2/3rd's full. When oil has reached it's temp, drop fries for 3 minutes. Prepare another set of baskets and rotate them for 3 minutes. 3 minutes down and 3 minutes up twice for each set of baskets. The total cook/rest time is 6 minutes each. Allow to drain well and turn baskets out on parchment lined sheet trays. and cool on a maxi rack in cooler.
As a cautionary note.....when you return the fryers to 350, you may have water in the bottom of the kettle. It will splatter so the safest thing to is stand back and partially cover the kettle with a 1/2 sheet pan. Do not cover completely or you will trap the steam and create a bigger issue and cause the kettle to boil over. The degree this happens to is dependent on how many pound of fries you blanch and how well you drained the fries so the best method is to blanch fries per shift or have a set of fryers specifically for blanching.
When cooled, fries can be held at room temp throughout the rush. They are place in baskets no more than half full in 350 degree fryer until golden brown. Remove from grease, drain well and turn out into station salting immediately. Only cook the amount of fries you can use in 5 minutes or less.
Take note that 5 guy's burgers has one person dedicated to cook fries throughout the shift. This is the best example of how dedicated they are to the fry. However, they blanch and handle them differently and even though their product is rather good, there is too much of the sugar/starch remaining in the potato. This causes their fries are a bit more dark in color than I personally like or believe they should be but........to each their own.
No respectable fry (pomme frites or the like) is ever going to be crisp more than a few minutes out of the fryer. The really need to be produced, served and consumed quickly and in a reasonable amount of time or there will always be issues. This boiling process is something I cannot understand. Potatoes seem to have more water content these days because they are not cured as long as they once were. That's the other thing....cured potatoes. I would order these specifically for fries and potato chips. My experience has shown me they work the best. There should be a vendor that has them on his list. If not, you'll need to order more and store them for more time. Anyhow, boiling them adds water and opens the pores of the potato allowing more grease to enter. Basically you're breaking down the potato and since it already has a higher water content, it's amplified. I guess the best way to know if you have a properly aged potato.......it's shouldn't be too soft but it's feel should "give" just a bit when squeezed. There should also be no green what-so-ever when you scrub the potato! I would also suggest using A Utility Potatoes. These are typically Idaho Russets but aren't sized like a 60, 80 or 120 ct potato. They arrive in a 50# sack and not a box. They are also oddly shaped and don't look as nice as they should for a baked potato. Then again, you're cutting them so it really doesn't matter