Mint Jelly Half is given out in a random event. I don't know if people also get it from the giant jelly or not.

There is nothing special you can do though to get the more rare jellies or omelettes.

I get Glowing Jelly 3x more than I get any other jelly. Poisonous twice as much. I hate them both. I'm thrilled when I get anything else.

I get much more varied omelettes including a couple of the newer ones. Fresh Fruit Surprise, Meat Feast and Tangy Tigersquash.