For example, Mishnah Pesahim 10:3 reads:

A. [They] served him—he dips the lettuce (HHZRT) [the vegetable used for the bitter herbs] before he reaches the bread condiment.

B. [They] served him unleavened bread and lettuce and hharoset [a mixture, e.g., of nuts, fruit, and vinegar pounded together (a post-mishanaic gloss adds “and two cooked foods,” a phrase which is not found in the MSS, which breaks the flow of the passage, which is not attested in the Tosefta analogue, and which is not assumed by the Gemarah); see Bokser, Origins, pp. 118–119, note 7, and David Halivni, Sources and Traditions, Tractates Erubin and Pesahim (Jerusalem: Jewish Theological Seminary of America, 1982), p. 574, note 5)] even though the hharoset is not a commandment R. Leazar b. Sadoq says, [It is a] commandment.

C. And in the Temple [they] [post-mishnaic gloss adds: “used to”] serve him the carcass of the Passover offering.