Other than being something a poor person would use, and that Zen monks are typically quite poor, Tenkara has nothing to do with Zen. Perhaps you mean Japanese (not the same thing) rather than zen. I think people in the west use the term "zen" for a lot of silly things, in complete ignorance of its origins, which is fine. But it is a little more "off" when you are talking about another thing (Tenkara) that also has a nominal Japanese origin.
Minimalism is not the same thing, and the Japanese aesthetic of wabi-wabi that has leaked into Japanese Zen (and not the other way around) is actually a lot more interesting and complicated than simple minimalism. I don't see much wabi-sabi in tenkara either, unless you are old a broken and using a old broken and repaired pole, in a leaf-covered stream, to catch a fish that is old, bored, and full of parasites.
/lecture off :-)