Toss shallots with oil and 3 teaspoons thyme on small rimmed baking sheet.
Sprinkle with salt and pepper.
Bake until golden, about 25 minutes.
Mix 1 tablespoon vinegar and 1 tablespoon sugar in small bowl.
Drizzle over shallots; toss to coat.
Continue roasting until shallots caramelize, stirring occasionally, about 10 minutes.
Remove from oven.
Bring Port, brown sugar, 4 tablespoons vinegar, and 1/2 cup sugar to boil in heavy large saucepan over medium-high heat, stirring until sugar dissolves.
Add cranberries and currants; cook until berries pop, stirring occasionally, about 8 minutes.