Pesachim 44B

ליתן טעם כעיקר. שאם שרה ענבים במים, ויש בהן טעם יין ⁠— חייב.

comes to establish the principle that the legal status of the taste of a forbidden food is like that of its substance. This term teaches that any food that absorbs the taste of a prohibited item assumes the status of this prohibited item itself. As, in a case where one soaked grapes in water and the water has the taste of wine, a nazirite is liable for drinking this mixture, as it assumes the status of wine.

מכאן אתה דן לכל התורה כולה: ומה נזיר שאין איסורו איסור עולם, ואין איסורו איסור הנאה, ויש היתר לאיסורו ⁠— עשה בו טעם כעיקר, כלאים, שאיסורו איסור עולם, ואיסורו איסור הנאה, ואין היתר לאיסורו ⁠— אינו דין שיעשה טעם כעיקר?

From here you derive the halakha with regard to the entire Torah; in all cases, the legal status of the taste of a forbidden food is like that of its substance. The Talmud elaborates. Just as with regard to a nazirite, whose prohibition against eating grapes is not an eternal prohibition, as he will be permitted to eat grapes once his period of naziriteship is over, and furthermore, his prohibition is not a prohibition against deriving benefit from wine, and there is dissolution for his prohibition against eating grape products by requesting a Sage to release him from his vow, nevertheless, in his case, the Torah rendered the legal status of the taste of food forbidden to him like that of its substance; with regard to a forbidden mixture of diverse kinds, whose prohibition is an eternal prohibition [issuro issur olam] and whose prohibition is a prohibition against deriving benefit, and there is no dissolution for its prohibition, is it not right that the Torah should render the legal status of the taste of its forbidden food like that of its substance?