1. Bring a large pot of water to boil. Salt the water (about a tablespoon) and add the yuca. Cook according to the package instructions, or until fork tender (about 15-25 minutes).
2. Drain the yuca and remove the woody stems from the core. Season with salt and pepper and mash until smooth.
3. Take a heaping tablespoon of yuca and flatten in palm of hand. Place a cube of cheese in center and pinch the yuca around the cheese to form a ball. Repeat with remaining yuca and cheese.
4. To fry, heat oil over high heat. Oil should be about 1/2-inch deep.
5. Add yuca and cook for 1-2 minutes per side, or until golden brown. Remove from oil and drain on paper towels. Serve with guava dipping sauce.

For the sauce:

1. Microwave the guava paste and vinegar until melted and stir until the consistency of barbecue sauce. Add additional vinegar if necessary, to thin.