Cross-contamination happens when something unsafe moves to food that will not be cooked again. Raw chicken juice dripping onto cut salad, the same knife used for raw fish and then for paneer, or a cloth wiping a raw meat board and then a serving plate are classic examples. Allergens such as peanuts, tree nuts, shellfish and gluten can be transferred the same way.
Refrigeration layout is one of the main defences. Raw meat, poultry and seafood should be stored below ready-to-eat food, in covered containers, so nothing can drip down. Separate cabinets or clearly separated shelves for raw and cooked items, colour-coded containers and labelled GN pans all reduce mistakes. In display cases, raw and cooked products should be physically divided, with separate utensils.
A multi-cuisine restaurant in Bhopal might dedicate one undercounter on the tandoor station to raw marinated meats, keep cooked gravies and dairy in a separate reach-in, and store salads and garnishes at the top of the cold line, well away from raw items.