Chulin7: 4
יָרֵךְ שֶׁנִּתְבַּשֵּׁל בָּהּ גִּיד הַנָּשֶׁה, אִם יֶשׁ־ בָּהּ בְּנוֹתֵן טַעַם, הֲרֵי זוֹ אֲסוּרָה. כֵּיצַד מְשַׁעֲרִין אוֹתָהּ? כְּבָשָׂר בְּלֶפֶת.
A thigh in which the sinew of the thigh was cooked — if it contains the amount that can receive a flavor, it is prohibited. How do we evaluate it? Like meat in turnips.