Slice potatoes into thinner french-fry shapes. I like to cut mine where they're about the size of your typical fast-food fries.
Place cut fries in cold water. Rinse.
After rinsing, place cut fries in fresh cold water and allow to soak for 3-6 hours or overnight in the fridge. This step is super important - don't shortcut!
After soaking, dry potatoes as thoroughly as possible. I like to just spread clean kitchen towels on my kitchen island, spread out cut fries onto the towels and then blot with more clean kitchen towels.
While fries are drying, heat up oil in a pot to 275 - 300 degrees. You just need enough oil in the pot for a decent deep fry.
Fry fries in 275-300 degree oil for about 3-5 minutes. This is the first frying - they will NOT be crunchy so don't worry about that at this point.
After frying, place fries onto a paper-towel lined platter or dish to soak up any oil.
Keep as flat as possible, and place fries back into the fridge for 3-4 hours (I have also placed them in the freezer for about 1-2 hours).
When fries have cooled down, heat up oil (it can be the same as before) to 375 - 380 degrees F.
Fry fries in the hot oil until they look nice and crispy to your liking.
Remove fries from oil and drain as best as possible. Then place in a bowl.
While fries are still hot, season with salt to your liking!
Notes
This is the technique to use when you want the perfect, crispy-on-the-outside, soft-on-the-inside french fries at home. Don't skip any steps!