The variety of fresh fruits seems to depend on the season. This includes Watermelon, Oranges, Mangos, Pineapple, Pears, Papaya, Bananas, Apples, Craboo berries (sometimes raw, sometimes stewed), and Jicame slices.
The Jicame tastes like watercress and the Mangos are sometimes sliced green (a different variety?) and served with a salt and pepper blend.
If you get lucky, you will run into someone selling Wangla, think of a thin peanut brittle made with thousands of sesame seeds.
You will likely run into kids selling various Cakes, Peanut Brittle and Fudge Squares. Don't forget to get some Carmeled Popcorn from Melbourne, it is great for a hotel dessert (the hotel staff just loves this mess too.)(tip)
As far as the late night Meat and Burrito venders go, it is usually dark and things come out of 5 gallon buckets. My advice is to go with the flow of the locals. I know it smells great.
*Note- If on the bus from Belize City to San Ignacio, have a couple of dollars ready for the vender kids that will be wanting your attention as the bus rolls into the Belmopan bus station. On my last trip I bought 2 diet cokes, 2 plantain chips and some fudge.