Knead all of the ingredients together at low speed for 5 minutes and then at high speed for 5 minutes or until the dough is even. Leave the dough to rest at room temperature for around 20 minutes, covered with a plastic sheet. Add Crystal mix (Crystal Melange) and perform one book-fold sequence. Rest for 5 minutes and perform another book-fold sequence. After another 5 minutes, form the croissants and leave to rise at 30°C/32°C with 70% RH for 60-90 minutes. Bake for around 20 minutes in a static oven at 180°C or in a fan-assisted oven at 160°C.