On a work surface, mince the garlic with a pinch of salt. In a mini-processor, combine the garlic with the saffron, lemon juice and cayenne and pulse until blended. Add the mayonnaise and pulse until smooth. With the machine on, add the oil in a thin stream and blend until emulsified. Transfer the rouille to a bowl and season with salt.
Make Ahead
The rouille can be refrigerated for up to 3 days.
Serve WithGrouper Chowder.