Line a full-size sheet pan with parchment paper. Place a wire cooling rack over the sheet pan and spray it with nonstick oil spray. Place the sheet pan near a marble surface. Have 3 pairs of latex gloves available.
Pop the corn in a large pot with the canola oil. Once it is all popped, reserve at room temperature. Continue with the recipe the day it is popped to ensure freshness.
In the meantime, place the sugar and the salt in a saucepan with about one-quarter of its weight in water or enough to obtain a wet-sand texture. Add the lemon juice to prevent crystallization. Make sure there are no sugar crystals along the inside of the pot and that all the sugar has been hydrated.
Cook the sugar over high heat until it reaches 170°C / 338°F. Turn the heat off and gently stir in the popped corn. Make sure all of the popcorn is coated with sugar, then pour it over the greased wire rack.
Put on the 3 pairs of gloves and spray nonstick cooking spray on them. Working very quickly, separate the popcorn clusters into individual pieces and immediately place them on the marble once they are separated to cool quickly.
Once they have cooled, reserve them in an airtight container at room temperature. As long as they are kept in a cool, dry place, they will last for up to 10 days.