What is Horseradish vegetable called in Cantonese with how to pronounce and transliteration in english?

辣根

The above answer is correct, but not quite what the question asked. Yes those are the Chinese (Cantonese, written is the same in China, though there is simplified vs traditional) characters for horseradish, but the poster also asked how it is pronounced. Mandarin pin yin: là​gēn, Cantonese pin yin: laaht gān