LaVerne Birthday lunch for 10?
Either Shogun or Miyabi, both of which are Teppan-Yaki places, are fun with a group of that size. Both are on Foothill in La Verne. Grapevine, a Mediterranean place that is also good with a large group, is also open for lunch.
You might have a few more options if you expand the geographic area to include Claremont to the east and Glendora to the west.