Complex sentence: They have time ranging from 20 minutes to 35 minutes (usually 30 minutes) to shop and cook a dish and complete four platings (three for the judges and one "beauty plate") before time runs out.
Split into simpler sentences: They have time ranging from 20 minutes to 35 minutes to shop and cook a dish. The chefs must complete four platings (three for the judges and one "beauty plate") before time runs out.