First, make the relish.
Combine all relish ingredients and mix well. Leave in the refrigerator at least 1 hour before using.
Combine all the meatball ingredients and mix well. Form into 24 equal sized balls.
Heat a few tablespoons of oil. Shallow fry the meatballs until browned on all sides, adding more oil when necessary. Transfer to a paper towel lined plate to absorb excess oil.
Combine all the sauce ingredients in a food processor and puree. Transfer to a large saucepan.
Bring to a boil and cook for 15 minutes. Add meatballs. Reduce to a simmer and cook for another 5 minutes, stirring once in a while, adding water as necessary if sauce becomes too thick.
Let's make the sandwich now.
First, fry the queso de freier. Just put it in a hot skillet sprayed with non stick spray and fry until golden brown on both sides.
Now split you roll in half and spread some of the sauce from the meatballs on the bottom half of the roll.
Place a few slices of the fried cheese. Slice a few meatballs and then place your meatball slices on top.
Top with a little of the pineapple relish.
Top with the other slice of bread.