What are the food rituals of Buddhism?
There are a number of rituals within Buddhism resolving around food. Within Zen buddhism, a common ritual is to offer food from your plate to ghosts.
This is often done during a sesshin (a period of intense meditative focus) where a bowl is passed between those who assemble to eat. Each person will take a piece of food from their plate, place it onto their forehead for a short time and then into the bowl.
This is done to as the hungry ghosts symbolically represent our greed, our disappointment and all the unhappiness this brings. By giving away a piece of their meal, the Zen monks remove themselves from the wanting of food.
Alms-giving is also a common food ritual. At the birth of Buddhism, Buddhist monks did not live together in monasteries but instead were travelling beggars who relied on others for food.
Whilst this is no longer the case, Buddhist monks in Theravāda areas walk from their monastery with bowls, where they will continue to silently walk single file whilst local people fill those bowls with food and other offerings, such as incense.
When out walking, these monks will often wear hats which obscure their vision so that they cannot see who gave them the alms. This is done because it removes the notion of a giver and receiver and simply focuses all attention onto the acts of actually giving and receiving.
To add on to the above answer, monks and nuns of Theravada Buddhism depend entirely on alms from the laity for sustenance. As they are not allowed to have an occupation, basic needs like food, clothing, shelter, and medicine must be provided for them. In this case, it becomes more of a daily custom than a ritual, but it's fascinating nonetheless.
Buddhists believe that they should refrain from eating at the wrong time. They only eat from sunrise to noon. They also believe that they should refrain from taking food at an unseasonable time (which is after the mid-day meal). Offering food is also a food ritual. Food is given to monks during alms rounds and is also ritually offered to deities and ghosts to remind oneself to not be greedy and selfish.