Q. Can someone that does not eat gebrochts (matza or matza flour dipped or mixed with water) on Pesach dip or spread matza with mayonnaise? How about butter or jam?

A. Those who are stringent regarding geborchts, may allow matza to come in contact with mei peiros.or pure fruit juice, since exposure to mei peiros will not cause flour to become chametz. (See Sha’arei Teshuvah 460: 10, Eishel Avraham (Butchach 462) and Mikroei Kodesh (2: 15). However, the above applies only to pure fruit juices that do not contain any water. When water was added, on the contrary, it accelerates the process of fermentation.
Mekadesh Yisroel (396), Shevach Pesach (p. 193), Shaar Hamoadim (p. 169), and others quote different opinions in regards to butter and other spreads to be used on matza for those who do not eat gebrochts.
Minhagei Maharitz Halevy (p. 120) mentions that he would permit solid paste type spreads, such as butter, avocado, mayonnaise, banana, jam and similar, as opposed to liquids that run, flow and moisten.
Horav Shlomo Miller’s Shlit’a opinion is that there are different established minhagim in regards to butter that could have been manufactured from milk that had water added to it.
Jams are usually made from fruits cooked in water and contain a percentage of it.
Mayonnaise also contains a water percentage, however it is emulsified in the oil, and does not maintain the normal water properties. Therefore, there may be a reason to be lenient.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit’a