Why specifically an apple in the Charoses?
When we dip the maror into the charoses, we are telling a story. Not a story of sweetness—but a story of blood, of mortar, of suffering, and of birth. The story of the women of Israel who gave birth in hiding—out in the fields and between furrows of clay—when the pain of labor mixed with the mud and the blood was absorbed into the earth. Between the clay of the bricks and the “Livnas HaSapir,” between the depths of the Nile and the shade of an apple tree, an ancient secret is hidden—the secret of the Geulah that grew out of the lowest place.

The Daily Chizuk of our teacher, the holy Rebbe, the Gaon HaTzaddik Rabbi Eliezer Berland shlit"a — Wednesday, 22 Sivan 5785

Edited from the shiur delivered by The Rav shlit"a on 25 Nissan; these are his holy words:

What does an apple have to do with charoses? Charoses is mortar—it needs to have mortar in it, to remember how they sank into the mortar, how they went down into the mortar.

Like Rachel, the daughter of Meshutalach’s grandson (Pirkei d’Rabbi Eliezer 48 — “Rabbi Akiva says: Pharaoh’s taskmasters would beat Israel to make the quota of bricks double, as it says, ‘And the quota of bricks that they were making yesterday and the day before…’ And the Egyptians did not give straw to Israel, as it says, ‘Straw has not been given to your servants.’ So Israel would gather stubble in the wilderness and load it on their donkeys—along with their wives, their children, their grandchildren, and their granddaughters. And the stubble of the wilderness would pierce their heels, and blood would come out and mix into the clay. Rachel, the daughter of Meshutalach’s grandson, was pregnant and ready to give birth; she was trampling in the clay with her husband, and the baby came out from her womb and became mixed into the clay. Her cry rose before the Throne of Glory. That night the angel Michael descended and brought him up before the Throne of Glory; and that night Hashem descended and struck the firstborn of Egypt, as it says, ‘And it was at midnight, and Hashem struck every firstborn…’”). While she was trampling in the mortar, the baby became churned and mixed into the mortar.

And this is Livnas HaSapir—“And beneath His feet was like the work of Livnas HaSapir” (Shemos 24:10). Livnas HaSapir was a stronghold of closeness and love. But the apple is: “Under the apple tree I awakened you” (Shir HaShirim 8:5).

It is written in the Hagahos Maimoniyos: “Under the apple tree”—that there was not a single barren woman; “There shall not be among you a man or woman who is barren, nor among your animals” (Devarim 7:14)—there was no barren woman in all of the land of Egypt; all the women were remembered (with children).”

“All the women were remembered. They would run out to the fields. The Egyptians placed guards over every woman giving birth—at the second the baby would come out, the commando would immediately arrive: the reconnaissance unit, the naval commandos. They would snatch the child and throw him into the Nile, or bring him to Pharaoh to slaughter him.”

“Like the seven maidens of Basya: they saw a Jewish child in the middle of the Nile and said, ‘How great! How wonderful! We’ll bring him to Pharaoh so he can slaughter him, so he can bathe in his blood.’”

“Rashi says the angel Gavriel came—what did he do to the maidens? He sent them to Gan Eden or to Gehinnom; it is not yet known exactly. The moment they wanted to take the baby—Moshe—they wanted to throw him into the Nile. They said to her, to Pharaoh’s daughter: ‘What about honoring your father and mother?’”

Why didn’t she listen to her father? Because she had compassion on him. She took him and saved him; instead of choking him, she saved him.

What kind of daughter is this? A rebellious and defiant daughter! She doesn’t listen to her father.

That day Basya converted, and she was entirely afflicted with tzara’as. The moment she touched Moshe’s ark, the tzara’as disappeared.

They were “under the apple tree.” They hid under the bushes, and there the baby was born—“On the day you were born, your umbilical cord was not cut” (Yechezkel, chapter 16). There is an emphasis on both the first reish and the second reish—to teach that angels descended, cut the umbilical cord, and swaddled the babies.

“Honey from the rock, and oil from the flinty stone” (Devarim 32:13)—they all swam in a sea of oil, in a sea of honey.