What Is Karpas?

As mentioned yesterday, the karpas is an unknown vegetable. This miמhag is sourced in the Gemara (פסחים קיד ,א), but it only mentions that it should be a vegetable; it is dipped before the meal to arouse the curiosity of the children (שו"ת הרשב"א המיוחסות לרמב"ן סי' ר"ב).
The Mahari"l was the one to say that it should be a vegetable called "כרפס" as it contains the words "ס פרך - sixty (i.e. sixty myriads, 600,000 total) worked hard," a reference to the number of Jews who were enslaved in Egypt (מהרי"ל הל' סדר ההגדה, הובא במג"א סי' תע"ג סק"ד).
Problem is that we don't really know what "karpas" is. The Mahari"l gives a translation ("איפך"), but that is also not clear. R. Nosson Adler, the teacher of the Chasam Sofer, toiled diligently to identify the abstruse vegetable. He concluded that it's celery. The common old word for this was "אפיא" (similar to the original word of the Mahari"l). The Chasam Sofer gave a hint to the signifigance of this vegetable, as the letters are an acronym for the words "א-ל פועל ישועות אתה."
שו"ת חתם סופר או"ח סי' קלב
ועי' שם לעוד רמזים במיני מרור
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Why is it Called "Minchah?" Part III

...Finally, one more reason:
When the three angels came to Avraham to inform him of the birth of a son, Yitzchak, Avraham fed them much bread. The Ramban (בראשית יח, ו) explains that the abundance of bread that Avraham brought them served as an Olah offering, thanking Hashem for the good news. The prosecuting angels on high were quick to accuse "Look, he's offering to mere angels and not to You, Hashem!" Hashem replied "Rest your case; you will see - I will ask him to offer his own son, and he will do so without hesitating (סמהדרין פט, ב)." And so it was.
Now, at this meal, an accompanying Minchah was not offered. On the way to perform the Akeidah (which was born out of the prosecution by the meal above), Yitzchak noticed that his father was prepared to repeat his mistake: he was ready to offer Yitzchak as an Olah without a Minchah. "What's this - an Olah without a Minchah?!" Yitzchak exclaimed, "I will institute a tefillah in place of the missing Minchah," Yitzchak concluded. Hence, the prayer bears that name.
של"ה חלק תורה שבכתב דרוש לפ' וירא סי' יד-טו
ועי' בפי' זרע יחצק למשניות ברכות פ"ד מ"א שמביא א"ז בשם המדרש שאינה ת"י
ועי' עוד בס"ספר החיים" (אחי המהר"ל) כעין דברים הללו, ואפשר שמשם שאב השל"ה דבריו
ועי' עוד בענין שם מנחה בחי' חת"ס פסחים קז, א ד"ה סמוך למנחה. ספר "תוספת ברכה" בראשית כד, סג. תיו"ט ברכות פ"ד מ"א
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Why is it Called "Minchah?" Part II

...Developing this idea, some point out the lesson to be learned from the sun's descent in the latter part of the day: just as the sun bows towards and offers itself to its Creator, we should offer ourselves as well.
Others explain the title "Minchah" and the lesson therein as follows: The morning Tamid was offered as atonement for all the nocturnal wrongdoings, whereas the fats and limbs that were burned in the evening served as an atonement for the day-time sins. What purpose did the afternoon Tamid serve? Nothing - it was a selfless gift to G-d. As such, a most befitting title would be simply "Minchah - present."
To answer the question as to why Eliyahu was delivered specifically at the time of "Minchah" and to explain it's unique qualities, the Aruch Hashulchan explains that the minchah was the last offering of the daily service in the Beis Hamikdash. As such, it had the power of the "concluding offering," similar to the power of Ne'ilah on Yom Kippur. Thus, it deserves to have a namesake.
שו"ת רמ"ע מפאנו סי' כ"ב
שו"ת אמונת שמואל סי' כ הובא באלי' רבה סי' רל"ב ס"ק"א
ערוך השולחן ריש סי' רל"ב
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Why is it Called "Minchah?" Part I

Jews pray three times a day: morning, afternoon, and evening, or Shachris, Mincha, and Ma'ariv. Shachris means "morning," a suitable name for the morning prayer. "Ma'ariv" means "evening," a suitable name for the evening prayer as well. "Minchah" means "offering" - how does that match up?
The tefillos were established correspondent to the korbanos in the Beis Hamikdash. Two daily offerings were brought, corresponding to Shachris and Minchah (the fats and other limbs burned all night, hence the Ma'ariv prayer.) Along with the Korban Tamid, a "minchah" was brought. But this was with BOTH Tamid's - why did the afternoon prayer specifically merit the name?
Tosafos (פסחים קז, א ד"ה סמוך למנחה) grapples with this question. They suggest that it's a reference to the passuk that describes Eliyahu's salvation at the "time of minchah" (מלכים א' יח, לו. ברכות ו, ב). But this itself begs the question - why meritorious factor of the "afternoon" attributed more to the minchah than the tamid?
Some suggest that the name has an entirely different meaning: When Adam sinned and Hashem surprised him with a visit, the Torah records the encounter to have been "לרוח היום." Targum translates "למנח יומא - when the day descends." Hence, the translation of "מנחה" is "descent," referring to the sun's descent in the latter part of the day when the Minchah is prayed.
אבודרהם תפילת מנחה ופי' הרמב"ן שמות יב, ו
תורה תמימה בראשית כד, סג הערה לו
ועי' בספר "הכתב והקבלה" (ויקרא ב, א) שמקשר פי' מנחה - שפלות עם פי' מנחה - מתנה
שו"ת הרמ"ע מפאנו סי' כ"ב
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