The Talmud talks of Truknin, or “Kuva d'Ar'a” (batter baked in a cavity in an oven), and its status in terms of having characteristics of bread. Mar Zutra established his meal with it, and recited “hamotzi”. Mar bar Rav Ashi added that one can fulfill his Pesach obligation with it, in matzah form. The Tur (O.C. 168) rules that the berakhah is hamotzi regardless of whether or not the meal is established on it, and the Beit Yosef disagrees (there and in Shulchan Arukh, O.C. 168:15), and only mandates hamotzi when the meal is established on it.

R. Yonatan Eibshutz (Chid. Rabbeinu Yehonatan) explains the nature of the dispute. The Tur understands that Mar bar Rav Ashi is arguing on Mar Zutra; his statement regarding Pesach is meant to indicate, regardless of whether or not the meal is established. The Shulchan Arukh, however, understands the two statements as complentary; the reason it is effective on Pesach is because the meal is thus established on it.

This issue has great impact on the laws of maztah, because matzah can only be made out of that which requires a berakhah of hamotzi. Thus, the question becomes, if something normally requires “mezonot”, but when a meal is established on it, earns a “hamotzi”, whether such an item is acceptable for matzah. Working backward, this also affects the issue of “mezonot bread”: if something is acceptable as matzah, can it ever suffice with a “mezonot”, if there is no establishment of a meal?

The Magen Avraham (168:9) questions those who claim that bread baked with oil requires a “mezonot” based on the fact that the Rambam rules that matzah baked with fruit juice is acceptable. (He does suggest a distinction between oil and fruit juice might be possible.) Many acharonim disputed the Magen Avraham’s question, in light of the “Kuva D’Ara” acceptability for matzah; apparently “hamotzi only when a meal is established” is sufficient.

R. Moshe Sternbuch (Moadim U’Zmanim, I, 86, in footnote; see also V, 322) suggests that there is a crucial difference between Kuva D’Ara and fruit-juice baked bread, and their status vis-a-is mezonot. The former lacks the form of bread, but has the taste; thus, under conditions of meal establishment, may be acceptable as matzah. The latter, however, has the form of bread, but differs in taste; this distinction may be crucial (and may differ between fruit juice, which may maintain a similar taste, and oil, where the taste may differ significantly). .