Slic the spam into about 8-10 slices depending on how thick u like it and put it in ziplock bag. mix oyster sauce soy sauce and sugar until the sugar is disolved and add to the bag with space marinate for about 15 min.
drain off marinade nd fry spam on each side over medium heat until slightly crispy or until desired doneness some people like to glaze the spam with marinade sauce after frying either way tastes great.
place a strip of nori on a cutting board or clean surface. place your musbi mold in the middle of the nori add sushi rice to the mold pressing down firm and evenly sot here is about 1-1 1/2 inches of rice dip the mold and your fingers in water as you go to prevent sticking.
Next remove hte mold from the rice now you will have a nice little block of rice right on the nori. add some of the cooked spam to the top wrap up one side of hte nori and stick it to the top of the spam, then wrap up the other side. just like you are wraping a nice little package. use a little water on your finger to seal if needed. serve warm.
some like it dipped in soy sauce some like it with ketchup and some like it as is.