Heat the olive oil in a medium skillet. Add the onion and sauté several minutes, until soft. Add the apples and continue to cook until they just begin to soften. In a large bowl, combine the onion-apple mixture with the remaining ingredients. Using your hands, form the mixture into 16 small patties. Refrigerate until ready to use. Preheat oven to 350°F. Place a skillet over medium-low heat and add some olive oil. Brown the sausages in two batches for about 2 minutes per side. Place on a parchment-lined baking sheet and bake in the middle of the oven for about 10 minutes, or until fully cooked.