There is an halacha called יין פגום (mentioned in Pesachim 106a and Shulchan Aruch Orach Chaim Siman 182) where if I drank a cup of wine for Kiddush or Birkat Hamazon and didn't finish all of it, I must either wash the cup or add more wine or a bit of water into it so I can drink from it again (I...

The Gemara Shabbos 140b states the following.. וְאָמַר רַב פָּפָּא: הַאי מַאן דְּאֶפְשָׁר לְמִישְׁתֵּי שִׁיכְרָא וְשָׁתֵי חַמְרָא — עוֹבֵר מִשּׁוּם ״בַּל תַּשְׁחִית״. וְלָאו מִילְּתָא הִיא — ״בַּל תַּשְׁחִית״ דְּגוּפָא עֲדִיף And Rav Pappa said: One who is able to drink beer and nevertheless drin...

According to various opinions, Ashkenazim may eat food that comprises kitniyot on Pesach (e.g., mixtures), if it is batel b'rov (see Peninei Halacha here). For example: foods comprising kitniyot additives are almost always batel b'rov, since additives are normally only added in small amounts. Fro...