Fritessaus or frietsaus ("fries sauce") is a dutch accompaniment to french fries, served popularly nationwide. it is similar to mayonnaise, but with at most 25% fat, is leaner and usually sweeter than mayonnaise. mayonnaise in the netherlands is required by the warenwet (wares law) of 1998 to contain at least 70% fat and at least 5% egg yolk before it may be called mayonnaise.

Source: Wikipedia