2 medium heads radicchio (about 1 1/4 pounds total)
3/4 cup golden raisins
3 tablespoons olive oil
3 tablespoons red-wine vinegar
2 to 3 tablespoons sugar
Coarse salt and ground pepper
Preheat oven to 350 degrees. Spread slivered almonds on a baking sheet. Toast in oven, tossing occasionally, until golden, 8 to 10 minutes; let cool.
Core radicchio heads; cut or tear into 1-inch pieces. Combine in a large bowl with the finely grated zest and juice of 1 orange, golden raisins, olive oil, red-wine vinegar, sugar, and toasted almonds.
Season with coarse salt and ground pepper; toss to combine. Serve immediately, or refrigerate, covered, up to 1 day.