In a medium size hotel pan, put chicken wings into 1 layer. Lightly sprinkle chicken wings with salt and pepper. Cover, refrigerate and let them marinade for at least an hour (maximum 5 hours).
When the wings are ready to cook, preheat oven to 300F. Put chicken wings in a clean roasting pan that is large enough to hold the wings in one layer. Do not stack them or they won't cook evenly.
Then submerge the wings completely in grapeseed oil. Cover the pan with aluminum foil and bake at 300F until the wings are very tender (not falling apart), approximately 45 minutes to 1 hour.
When the wings are done cooking, use a slotted spoon and remove them from the fat. Transfer them on a sheet tray. Strain the fat and pour them in a clean pot. The oil can be kept for up to a month in the fridge.