In honour of Lag b'' Omer, here are some videos and links, and all about coloured eggs....
Rabbi Alon Anava - Celebrating the Hilula of Rav Shimon Bar Yochai
A Lag B''Omer tish - with Rav Dov Pinson in Flatbush last year. [Tish means ''table'', fahbrengen means ''get together'']
What is the Chabad custom regarding eating browned eggs on Lag BaOmer?
by Rabbi Levi Garelik - an halachic authority in Brooklyn and Brussels who is also Dean of TheOnlineRabbi
1. In Sefer Haminhogim [page 43] it says that the Mitteler Rebbe would eat hard-boiled eggs on Lag Ba'omer.
2. In "Lubavitch Vechayoleho" it says that the Rebbe Rashab would eat hard-boiled eggs on Lag Ba''omer, as well.
3. In "Otzar Minhogei Chabad" it is written that "it is told" that the Rebbe would eat hard-boiled eggs on Lag BaOmer and that their shells were colored brown during the cooking process. However, he does not write any source.
When I was a student in the Yeshiva, I had "heard" something about this but was never able to get to the bottom of this. [In those days no one spoke about customs in the Rebbe's home…] However, when I merited to get married to the daughter of one of the Rebbe's secretaries, Rabbi Binyomin Klein, I was told that a year earlier, on Lag Ba''Omer, my father-in-law called home and told my wife and her sister to quickly prepare "the colored eggs for Lag Ba''Omer." They had no clue what he was talking about and how do you "color" an egg?
So they called "Bubby Shusterman" [the wife of the Rebbe's "Baal Koreh" whose yahrzeit is in these days] who was a source of information. She explained that on Lag Ba''Omer it is customary to eat eggs that are colored, and that is done by boiling the eggs, and during the boiling process you insert in the water the shells of onions and this turns the eggs to the color brown.
Basically, the eggs are colored because that symbolizes transforming [or "coloring"] darkness - as eggs are a sign of mourning - to light. May we merit to celebrate this Lag Ba''omer, together with Rabbi Shimon Bar Yochai!
What's the reason or meaning of this minhag? It's for the students/ talmidim of Rabbi Akiva and the eggs end up a kind of bloody color. We do this davka on Lag BaOmer because it's the Hilulah [Yahrzeit] of Rabbi Shimon Bar Yochai [the Rashbi], who emphasized that the day of his death should be a day of simcha.
Another reason for colored eggs is that eggs are for aveilus [mourning], and we ought to mourn the passing of the Rashbi, but because the Rashbi wanted the day to be joyous, we color the eggs. we were told as kids coloured eggs are to remember that no [coloured] rainbow occurred during the life of Rashbi.