Sudden bout of nausea followed by numbness of the mouth and tongue. is that food allergy reaction?

Yes: Most likely a problem with oral allergy syndrome which is a cross reactivity issue with certain raw fruits and vegetables which have similar protein structures to some pollens like ragweed, birch tree, grass or mugwort.

Certainly possible: Food intolerance/allergy can manifest as a variety of symptoms. The most worrisome is difficulty breathing and throat swelling. Recurring numbness or tingling with specific foods only strongly suggests an immunologic reactivity to those foods that should be avoided. Blood testing can confirm an immunologic response to these foods and guide an appropriate diet strategy.

Food allergies: Milk, eggs, wheat, soybeans, fish, crustacean shellfish, tree nuts ; peanuts cause 90 % of food allergic reactions. Up to 15 million americans suffer from food allergies ; need to avoid not only certain foods but any ingredient that contains proteins derived from them. In some cases, anaphylaxis can result. See http://www.Boston.Com/lifestyle/health/blog/nutrition/2013/11/the_dangers_of_dining_out.