The Culinaromancer is too strong to be defeated until you've defeated the first five bosses. You can leave and stock up after defeating one boss without losing your progress in the fight. Sharks or higher healing foods are recommended during the fights, especially if you have low defence or little armour. If you try to enter the portal before finishing Desert Treasure, a message will appear saying "You need to have completed Desert Treasure to access this portal." Likewise if you have not yet completed Horror From The Deep.