There are two different customs regarding the issue of eating roasted meat or chicken at the Seder: some have the custom to eat such foods, whereas others are accustomed to specifically refrain from eating these foods. The practice in our community follows the second custom, and we make a point not to eat roasted meat or chicken at the Seder. The reason for this custom is that we do not wish to give the mistaken impression that we partake of the actual Korban Pesah (paschal offering), which was brought during the time of the Bet Ha'mikdash. In order to dispel any such misconception, we refrain from eating meat or chicken that was roasted, which would thus resemble the meat of the Korban Pesah which was always roasted in preparation for consumption.
When we speak of "roasted" meat, we refer to meat that was baked in its own juices, such as on a grill. Today, roast beef and roast chicken are generally baked in a gravy, and such food is permissible for consumption at the Seder, even according to our custom. The Kaf Ha'haim (work by Rav Yaakov Haim Sofer, 1870-1939) rules that even if the gravy dries as a result of baking, we do not consider the meat to have been "roasted" and it may be eaten at the Seder.
It should be noted that this custom applies only to meat and chicken. One may eat other roasted foods, such as roasted eggs, potatoes and vegetables. Furthermore, this custom refers only to the Seder; one may eat roasted meat and chicken at other Pesah meals.
This custom affects the issue of eating the Zero'a – the shank bone that we place on the Seder plate. If the shank bone had been roasted, one must ensure not to partake of it at the Seder. If, however, it had been boiled or cooked in a gravy, then it may be eaten at the Seder. One who chooses to eat the Zero'a at the Seder should not make any comment to the effect that he does so in commemoration of the Korban Pesah, so as not to give the impression that he partakes of the actual paschal offering.
Summary: The practice in our community is not to eat at the Seder any meat or chicken that was roasted, meaning, that had been cooked in only its own juices. One may eat meat or chicken that was boiled or baked in a gravy.