Regarding the Seudat Hamafseket, which is the Seuda (meal) that is eaten right before the fast of Tisha BeAv. There are some restrictions that are made how to eat that meal. The reasons these restrictions were made was because it was at that time when the enemies entered the Bet Hamikdash, and they started eating and drinking, and they started reveling, and therefore to remember what they did, so we minimize our pleasure and we limit our eating before the fast. And therefore, Halacha says, that the Seuda right before the fast, we should only eat one cooked food, and not more.
One cooked food would mean ,for example a food that’s normally cooked together, even if it has 2 items in the food. For example, Majedra (rice with lentils), even though technically it’s rice and it’s lentils, since it’s cooked together, that would be considered one cooked food.
Halacha tells us that bread with the Seuda is not considered a cooked food. So bread with a cooked food would be considered permissible.
Some people have a question regarding pickles and things like that, which are put into vinegar for a time. Halacha says pickled items are also considered like cooked. So technically if a person has a pickle during the Seuda Mafseket, so that’s his item.
In any event, there are some opinions that are even more stringent, on let’s say a cup of coffee, which is cooked, and it becomes the one item. So therefore a custom evolved, to have a meal prior to the Seudat Hamafseket. Which means a Seuda in order to eat whatever you like. And then when you get close to the time of the fast, then already you sit down and have a piece of bread with a little salt, or some have the custom to have a hard boiled egg. Some people even have the custom to sit on the floor in Derech Avelut (the way of mourning). So having a meal prior would be a way, not to get around it, but it’s a legal way to have an official Seuda before hand. Do not fill yourself up obviously at that early meal. Finish that meal, and then take a walk and come back, and then have the official Seuda Hamafseket with one cooked item.
It should be pointed out that there is no Zimun when 3 men are sitting together at Seudat Hamafseket. It’s not a festive meal where you get together. On the contrary, it’s considered as if a person is eating on his own. The Birkat Hamazon at the Seudat Hamafseket is the regular Birkat Hamazon. There are no additions commemorating Jerusalem at the Birkat Hamazon of Seudat Hamafseket.
***It should be pointed out that this Halacha applies when Tisha BeAv falls out Monday-Thursday and not Motsei Shabbat.
