Serve these savory small bites with roasted turkey or spiral sliced ham instead of Brie, if you like. If clementines are unavailable, substitute with sweet tangerines or canned mandarin oranges, drained thoroughly.
Zest clementines, reserving zest in a bowl. Peel and separate into segments and then cut into 1/2-inch pieces, discarding seeds as you go. Transfer to bowl with zest and set aside.
Heat oil in a small pot over medium heat. Add onions and cook, stirring occasionally, 3 to 4 minutes. Stir in vinegar and cook 1 minute more. Add fruit and zest, cardamom, salt, and pepper and cook, stirring gently once or twice, until juicy, 2 to 3 minutes more. Transfer to a bowl and set aside to cool. Top each cracker with a wedge of Brie and then a dollop of clementine chutney.