I've also heard it called "cro-knitting" or "cro hook" and using one long crochet hook, but with hooks at each end.
This page had some good descriptions. IMO, Tunisian is very different from Portuguese which can be done w/two "regular" non-hooked knitting needles
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Melinda
Knitting homeschooling mom to 3 kidlets
OTN:
Bayerische Socks by Eunny Jang in Knit Picks Risata (for ME!)
in queue: Swirl glittens; lacy raglan for me; new cabled sweater for dh