1. Soy, kimchi, olive oil, lentils and yogurt are the world's five healthiest foods. (Is this statement right in meaning and diction? What is 'soy'? Is 'soy' soy sauce or soybean in the sentence?)

Question

2. Today lunch is free in this restaurant.

3. Today lunch is for free in this restaurant.

(Which expression is right? Are both gramamtical?)

Answer 1

#1 is correct in meaning and diction. Soy is a bean that is used in many things. Check this site:
http://www.soya.be/

#2 is correct.