Take a piece of the bottom matzah, and some extra matzah if you like, and some more maror. Dip the maror in charoset, then shake off the charoset. Make a matzah-maror sandwich, recite or read or think about the following text, then eat the sandwich.

The text is:

Zecher l'mikdash k'hillel. Ken asah hillel bizman shebeit hamikdash hayah kayam. Haya korech matzah umaror v'ochel b'yachad. L'kayam mah shene'emar, al matzot um'rorim yochluhu.

Which means:

This is a reminder of what Hillel used to do in the time of the Temple. When the Temple stood, he used to combine matzah and maror in a sandwich and eat them together, doing as the Torah says: "They will eat the Pesach offering together with matzah and maror."