How did they get the ingredients for the food in the Medieval Times?

Most food was grown by serfs.

Fish was caught at sea and preserved by salting. In this form it was taken far inland.

Cheese was manufactured much as it is today, but without sanitizers and thermometers. Somehow they managed anyway The same is true of beer, wine, cider, and mead.

There was an active trade in much of the Middle Ages for exotic foods, and these included most spices and seasonings.