Using well water and wood ovens have become a rarity these days and we have accepted such changes; kids ask why then we do not accept eating onions, eating at hotels in keeping with changing times?

Using well water, and wood ovens is related to orthodox practices; one has to follow it to their ability. But eating onion is prohibited by the scriptures which will result in sin, it is like drinking alcohol.
Notes:
Purity in food results in a purified mind, “AhAra shuddhau sattva-shuddiH sattva-shuddhau dhruvA smrutiH”, is the Vedic statement; food influences our thoughts hence eating outside food should be avoided.