I have been in need of cilantro root for some time, and my typical source, Mekong Rainier, told me that they stopped carrying it. Here is a description: http://www.thaitable.com/thai/ingredi...
Fresh bunches of cilantro are usually sold with the roots removed. Mekong sold it in frozen form, kept in the freezer case, a product of Thailand.
Of course there are many Vietnamese-oriented markets in town, but I have not had luck finding this ingredient at such places in the past (or at the larger Asian supermarkets like Uwajimaya, H-Mart, 99 Ranch etc.) And I have been so reliant on Mekong that I have not sought out other more Thai- or Cambodian-focused markets.
Thanks in advance.