Step-by-step explanation:
A mixture in which solute particles are unevenly distributed into the solvent is known as a heterogeneous mixture.
For example, oil present in vinegar will unevenly mix together.
Whereas a mixture in which solute particles are evenly distributed into the solvent is known as a homogeneous mixture.
For example, salt dissolved in water is a homogeneous mixture.
Therefore, when a salad dressing is made by a chef by mixing oil, vinegar, and spices then it is a heterogenous mixture.