The Laws of Pesach - The Seder vol.4, no.13
Matzah: The Torah obligates us to eat at least an ounce (approximately) of matzah on the night of the fifteenth of Nissan (this year coinciding with March 21). The matzah must be matzah shmurah (made of only flour and water and specially supervised at least from the time of grinding the grain into flour). These criteria apply for the second night of Pesach as well.
The ounce of matzah should be eaten b’kdei achilus pras , a length of time of up to two, or according to some authorities, nine minutes. An ounce of matzah equals approximately one half of a hand baked matzah or two thirds of a machine baked matzah. These measurements are not exact as different matzahs have different densities. Therefore a local Rabbi should be consulted. One who is ill may be allowed to eat even less. According to some authorities if eating matzah is very difficult for an individual he may sip water (and only water, as other liquids annul the taste of the matzah) between mouthfuls or soak the matzah in water a little before eating. If one foresees he will have difficulty eating the matzah he should consult a competent halachic authority as to how to perform the mitzvah in the most proper manner. According to the Ashkenazic custom egg matzah is generally not allowed to be eaten for the entire Pesach except for extreme cases.
Four cups: Our Sages obligated us to drink four cups during the Seder. According to some authorities each cup should hold a minimum of 3.3 ounces. At least the majority of the cup should be drunk. It is actually preferable to drink the entire cupfull. One should try to drink this amount at one time. If this is too difficult he may drink it in up to two, or at worst, nine minutes.
The preferred beverage to drink is an unpasteurized, red wine with no sugar or water added. Other wines are also acceptable, even a high quality white wine. One may dilute the wine with up to two thirds water or grape juice according to many opinions as long as the taste of wine remains. This varies from wine to wine. Grape juice is acceptable but does not afford the aspect of symbolic "freedom". If one can absolutely not drink the above beverages, it is appropriate to drink certain beverages which are used to enhance a meal like coffee or tea. A Rav should be consulted.
Bitter herbs: One can use lettuce, horseradish, or endives for the mitzvah of Maror. One must eat at least an ounce of maror for the mitzvah itself as well as for the "Hillel sandwich". It should be noted that leafy greens are very often infested with insects that are very difficult to discern and need to be examined very thoroughly. It may be preferable to use Romaine lettuce stalks which are easier to examine. Jarred horseradish may not be used.
Afikomen: One must eat at least another ounce of matzah at the end of the meal called the afikomen. One should eat the afikomen before midnight. The mitzvahs of the matzah and four cups must be performed reclining.
Hagadah: It is a positive commandment to relate the story of our exodus from Egypt. All who discuss the story at length are considered praiseworthy.
