I finally found one! I have looked in just about every store in town trying to find a flat stainless steel grater. Most of the flat graters I found were framed in plastic and many were not stainless steel. Let me explain why those were not acceptable.
I do not use this style of grater only for grating. This tool comes in handy for draining pots as well. Plastic and boiling water are not friends, and any other shape would be awkward to use. Flat is also best when it goes into the dishwasher or is stored in the cupboard, taking up very little space. I learned from experience that stainless steel is a must. I had another one of these graters for years, but had to discard it when rust took over. Stainless steel is also harder and sharper.
While I still use other methods when grating large quantities, this is the perfect tool for quick jobs, and often it saves getting out, then cleaning up the colander. Although it was hard to find, I was pleased to pay only $5.99.