Day of Creation
The stars and the void between them is what is left of the gods, we must remember them.
An importent part of remembering the gods is the types of food that are consumed. They need to have a high contrast between dark and light.
Often this is done using dried pieces of fruit baked in bread, but poppy seeds are a common substitution. Other foods are various berries that have darker seeds.
It is commonly noted that the sky is mostly dark void with significantly less points of light, in contrast to the foods consumed. The religeous leaders claim that the gods made it that way so that there could be more light on the planet.
The tradition started after the grey war, as a way to bring the events of it into the culture and to help the population process what had happened.
While at the beginning it was a very positive event it has since been tarnished by the opressive leadership of the king. This in turn have turned to use the event as a call to change the world, often by skirting what is considered "high contrast " foods.
During the solstices one is only to eat items that have a stark contrast between light and dark. Furthermore one is supposed to have a high contrast lighting indoors, using only few lightsources.
Everyone is supposed to participate in some way and it is frowned upon to not do so, with some more extreme regions even punishing absentees.
The day of creation is observed twice yearly, at the solstices.