What does being holy mean?
How do we become holy?
Why are the only mitzvot where we are commanded to eat food associated with the holiday of Pesach?
Rambam- four levels in the hierarchy of creation
Level 1: Domaim – the silent, inanimate realm (i.e. earth and minerals) constitutes the lowest existence, and is self-sustaining.
Level 2: Tzomey'ach – vegetation is nurtured by the previous level, earth.
Level 3: Chai – the animal kingdom eats mostly vegetation.
Level 4: Medaber – human beings (lit.: the speaking being) derive nourishment by eating both vegetation and animals.
https://www.aish.com/ci/s/48916842.html
That which we use to become holy and pure can also be used to make us unholy and impure.
דהיינו כשהטוב המעורב בה נתברר מהרע וגובר ועולה ונכלל בקדושה. כגון דרך משל האוכל בשרא שמינא דתורא ושותה יין מבושם להרחיב דעתו לה' ולתורתו, כ(יומא עו ב): "דאמר רבא: חמרא וריחא כו'", או בשביל כדי לקיים מצות עונג שבת ויום טוב. אזי נתברר חיות הבשר והיין שהיה נשפע מקליפת נוגה ועולה לה' כעולה וכקרבן.
That is, it is absorbed within Sanctity when the good that is intermingled in it is extracted and separated from the evil, prevails [over it], and ascends to be absorbed in Sanctity. For instance, if one eats fat beef and drinks spiced wine not out of physical desire, but in order to broaden his mind for the service of G‑d and for His Torah,
as Rava said, “Wine and fragrance [make my mind more receptive],”
or in order to fulfill the commandment to enjoy the Sabbath and the festivals.
When one eats and drinks in the above-mentioned manner then the vitality of the meat and the wine which originated in kelipat nogah is then extracted from the evil and ascends to G‑d like a burnt offering and sacrifice (i.e., the life-force of kelipat nogah that the food and drink contain is absorbed in Sanctity).
https://www.chabad.org/library/tanya/tanya_cdo/aid/7886/jewish/Chapter-7.htm