This paper presents a new complete and well-defined sample of flat-spectrum
radio sources (FSRS) selected from the Cosmic Lens All-Sky Survey (CLASS),
with the further constraint of a bright (mag less than or equal to 17.5) o
ptical counterpart. The sample has been designed to produce a large number
of low-luminosity blazars in order to test the current unifying models in t
he low-luminosity regime. In this first paper the new sample is presented a
nd the radio properties of the 325 sources contained therein are discussed.