I know this isn't Sosua... but empanadas are a favorite of mine.
In Cabarete within the last few weeks we have two new options:
1) A-Bailar Cafe across from the micro-golf has them on lunch & dinner menu at 50 pesos each. Beef, chicken, or vegetable. Two for 100 pesos with salad. They also have fried yuca balls (larger than a golf ball) with mozarella inside, 50 pesos also. All very good for a snack or lunch... or just an appetizer before dinner. Personally I'm partial to the beef empanadas & bolas de yuca.
2) There's been a cart at Scotia Bank for the last few weeks. Haven't tried them, will report when I do.