(יד) וַיְמָרְר֨וּ אֶת־חַיֵּיהֶ֜ם בַּעֲבֹדָ֣ה קָשָׁ֗ה בְּחֹ֙מֶר֙ וּבִלְבֵנִ֔ים וּבְכָל־עֲבֹדָ֖ה בַּשָּׂדֶ֑ה אֵ֚ת כָּל־עֲבֹ֣דָתָ֔ם אֲשֶׁר־עָבְד֥וּ בָהֶ֖ם בְּפָֽרֶךְ׃
(14) And they made their lives bitter with hard service, in mortar and in brick, and in all manner of service in the field; in all their service, wherein they made them serve with rigour.
(ג) הביאו לפניו מטבל בחזרת. עד שמגיע לפרפרת הפת. הביאו לפניו מצה וחזרת. וחרוסת. ושני תבשילין. אף על פי שאין חרוסת מצוה. רבי אליעזר בר צדוק אומר. מצוה. ובמקדש. היו מביאים לפניו גופו של פסח:
(3) [Then] they set [food] before him. He dips the lettuce before he reaches the course following the [unleavened] bread. [Then] they set before him unleavened bread, lettuce, and a mixture of apples, nuts, and wine, and two dishes, although the mixture of apples, nuts, and wine is not compulsory. Rabbi Eliezer bar Tzadok says: It is compulsory. And in the Temple they used to bring before him the body of the Passover-offering.
צריך לשקועיה בחרוסת משום קפא ... ודילמא לעולם אימא לך לא צריך לשקועיה וקפא מריחא מיית ... ואמר רב פפא לא נישהי איניש מרור בחרוסת דילמא אגב חלייה דתבלין מבטיל ליה למרוריה ובעינן טעם מרור וליכא
One must submerge it in the ḥaroset, due to the kapa in the lettuce... Actually, I will say to you: According to the halakha, one need not submerge the lettuce in ḥaroset, and the kapa dies from the smell of the ḥaroset... And Rav Pappa said: A person should not leave bitter herbs in the ḥaroset for a lengthy period of time, lest the sweetness of the spices in the ḥaroset nullify its bitterness. And the bitter herbs require a bitter taste, and they are not bitter when marinated in ḥaroset.
(יא) הַחֲרֹסֶת מִצְוָה מִדִּבְרֵי סוֹפְרִים זֵכֶר לַטִּיט שֶׁהָיוּ עוֹבְדִין בּוֹ בְּמִצְרַיִם. וְכֵיצַד עוֹשִׂין אוֹתָהּ. לוֹקְחִין תְּמָרִים אוֹ גְּרוֹגָרוֹת אוֹ צִמּוּקִין וְכַיּוֹצֵא בָּהֶן וְדוֹרְסִין אוֹתָן וְנוֹתְנִין לְתוֹכָן חֹמֶץ וּמְתַבְּלִין אוֹתָן בְּתַבְלִין כְּמוֹ טִיט בְּתֶבֶן וּמְבִיאִין אוֹתָהּ עַל הַשֻּׁלְחָן בְּלֵילֵי הַפֶּסַח:
{This is from Maimonides' book of law, the Mishneh Torah, from the 12th century}
Charoset is a Mitzvah from the words of the storytellers, as a remembrance of the mortar that they used in Egypt. How do you make it? You take dates, dried figs or raisins and the like, crush them, add vinegar, and mix them in with spices just as clay is mixed into straw. This is placed on the table on the Seder nights of Passover.
שולחן ארוך הרב:תעג:לב
החרוסת צריך להיות עב לפי שהוא זכר לטיט שנשתעבדו בו אבותינו ואח"כ צריך לרבך אותן במשקה זכר לדם ויש לרכבו במשקה אדום כגון חומץ או יין אדומים ויש לעשות החרוסת מפירות שנמשלו בהם כנסת ישראל תחת התפוח עוררתיך. כפלח הרמון רקתך. התאנה חנטה פגיה. אמרתי אעלה בתמר. אגוז אל גנת אגוז ירדתי. ושקדים על שם ששקד הקב"ה על הקץ לעשות. ומעיקר הדין יכול לעשותו אפילו מירקות ולרכבו אפילו במים ושאר משקין אבל עכ"פ צריך ליתן בתוכו דבר שיש בו קיוהא כגון תפוחים או יין וחומץ זכר לשיעבוד שהיו משתעבדים בישראל עד שהיו שיניהם קיהות
לג- וצריך ליתן בתוכו תבלין הדומין לתבן כגון קנמון וזנגביל שאינן נדוכין הדק היטב ויש בהן לאחר הדיכה חוטין קשין וארוכין קצת כמו תבן זכר לתבן שהיו מגבלין בתוך הטיט
Shulchan Aruch Harav 373:32-33
32: The Charoset needs to be thick, as its a remembrance of the mortar that our ancestors toiled in throughout their slavery, and then afterwards you need to mix in liquid as a remembrance of the blood. Thus, ideally the liquid you mix in should be red, like wine or vinegar. The charoset should be made of the fruits that greeted the Israelites when they came into the land of Israel: apples, pomegranates, figs, dates, nuts and almonds. From a pure legalistic sense you could make it instead from vegetables, and mix in water or any other liquid, but in any event you need to put in something which has tartness (קיוהא) , like apples, wine or vinegar as a remembrance of the slavery with which they subjected our ancestors until their teeth became blunt (קיהות)
33: You need to put spices into the charoset that look like straw, like cinnamon and ginger, which aren't chopped into tiny pieces and they have strong and long threads, which makes them look like straw, as a reminder of the straw which the Israelites had to put into the mortar.
Rabbi David Seidenberg
Why isn't charoset explained in the Haggadah? Here's the answer that came to me...
The Talmud debates whether or not it's a mitsvah, but tells the story of the spice-sellers in Jerusalem, yelling out their shop windows "Spices for the mitsvah!" The essence of the Charoset in the Talmud is not that it should be sweet, but that it should be tart, like apples, and thick like mud. Rashi (but not the Talmud) gives a few interpretations of this: it's a reminder of the (tart) apple trees in Egypt under which Israel made love and gave birth; it's a reminder of the mud and straw (dates/apples and spices) for the bricks they made as slaves.
But the Hagadah doesn't put those meanings in order because, like the Talmud itself, it doesn't explain any meaning for charoset at all. Why?... I think charoset might the stuff of what happens when we can't separate out the symbols, when they get stuck together, when the slavery and freedom are mishmashed together. Like the wicked child's picture of the world, there's no separation between worship and enslavement (both are called "Avodah" after all). Like the tree of
knowledge, literally the tree of knowing good and evil, i.e., good and evil all mixed together, it represents our normal lives...
...So one more lesson of the Haggadah is: don't separate your normal muddled state from the holy and mystical and transformative; even if you're stuck in what is sour, in the mud, add the sweetness. Leave Egypt with all your possessions, the remnants of slavery, the hopes of freedom, and everything in between.