Cooking foods - How to check doneness
Cake or Custard
Insert a toothpick or a knife into the centre of the cake or custard, then pull it out. If it comes out clean, the cake or custard is ready.
Thickness, type and freshness all have a bearing on fish cooking times. However, a good rule of thumb is to estimate the cooking time on the basis of thickness alone: For baking at 190 to 230 °C, cook about 5-6 min per cm of thickness, as measured at the thickest point of the fish (filet, steak or whole) . Cooking is complete when the flesh turns opaque (as opposed to its translucent and glossy look before cooking) and breaks up easily, separating from the bones. To make sure, poke the fish with a fork: It is done when it flakes easily and does not stick to the prongs. Avoid overcooking as it dries fish out, makes it tough and tasteless.