Here is the full list of all 8 TasteMaker: Restaurant Simulator achievements.
Have 100 pieces of decoration in your restaurant
Have 25 employees
Lock 30 people in your restaurant
Sell 75 chicken dishes in a month
Have 10 people take a dump in your restaurant
Beat all 3 challenges of the first scenario
Beat all 3 challenges of the second scenario
Beat all 3 challenges of the third scenario