A fasting tart recipe found at Let Hem Boyle
In the liturgical calendar of the Western Christian churches, Ember (Ymber) days are four separate sets of three days within the same week — specifically, the Wednesday, Friday, and Saturday — roughly equidistant in the circuit of the year, that are set aside for fasting and prayer. These days set apart for special prayer and fasting were considered especially suitable for the ordination of clergy. The Ember Days are known in Latin as the quattuor anni tempora (the “four seasons of the year”), or formerly as the jejunia quattuor temporum (“fasts of the four seasons”).
The four quarterly periods during which the ember days fall are called the embertides.