Reference for Oktzin 2:5
הַמְחַתֵּךְ לְבַשֵּׁל, אַף עַל פִּי שֶׁלֹּא מֵרַק, אֵינוֹ חִבּוּר. לִכְבֹּשׁ וְלִשְׁלֹק וּלְהַנִּיחַ עַל הַשֻּׁלְחָן, חִבּוּר. הִתְחִיל לְפָרֵק, אֹכֶל שֶׁהִתְחִיל בּוֹ, אֵינוֹ חִבּוּר. הָאֱגוֹזִים שֶׁאֲמָנָן, וְהַבְּצָלִים שֶׁחֲמָרָן, הֲרֵי אֵלּוּ חִבּוּר. הִתְחִיל לְפָרֵק בָּאֱגוֹזִים וּלְפַקֵּל בַּבְּצָלִים, אֵינוֹ חִבּוּר. הָאֱגוֹזִים וְהַשְּׁקֵדִים, חִבּוּר, עַד שֶׁיְּרַסֵּס:
If one chops up [produce] for cooking, even if he did not complete the cut, this is not considered to be a connection [connecting the pieces together for matters of purity]. If [one chopped it up] for pickling, or for boiling, or for placing it on the table, this is considered to be a connection [for matters of purity]. If one began to separate [the pieces], the [part of the] food which he started [breaking off] is not considered to be a connection. If one strung nuts together, or tied a bunch of onions together, this is thereby considered a connection. If one began to take the nuts apart, or to peel the onions, this is not considered a connection. Regarding nuts and almonds [in relation to their shells], this is considered a connection, until one mashes them.