1. Peel sweet potatoes and cut into 1-inch chunks. Divide chunks equally between 2 lightly oiled baking pans (each 10 by 15 in.); cover tightly with foil.
2. Bake in a 450° oven for 15 minutes. Uncover and continue to bake until sweet potatoes are tender when pierced, about 25 minutes longer; switch pan positions halfway through baking.
3. Meanwhile, put jelly in a 2-cup glass measure. Heat in a microwave oven at full power (100%) until softened, about 20 seconds. Add vinegar and stir until well blended.
4. Combine sweet potatoes in 1 pan. Pour jelly mixture evenly over potatoes and turn chunks with a spatula to coat evenly. Continue baking until jelly mixture thickens and sticks to sweet potatoes, about 10 minutes, turning chunks often to prevent scorching.
5. Pour into a wide bowl. Sprinkle with cilantro and add about 3 tablespoons lime juice and salt to taste.