Makes 1 quart
1 cinnamon stick
1 teaspoon cumin seeds
½ teaspoon black peppercorns
3 cardamom pods, crushed
¾ cup distilled white vinegar
¼ cup sugar
Juice of ½ lemon
Kosher salt
6 thin slices peeled ginger
2 dried chiles de arbol
2 large firm mangoes, peeled and cut into ½-inch-thick wedges
Heat the cinnamon stick, cumin seeds, peppercorns and cardamom in a small skillet over medium-low heat, stirring, until toasted, about 4 minutes.
Make the brine: Combine the vinegar, ¾ cup water, the sugar, lemon juice, 1 tablespoon salt, the ginger, chiles and toasted spices in a medium saucepan; bring to a simmer over medium heat. Cook, stirring to dissolve the sugar, 5 minutes.
Pack the mango wedges into a 1-quart jar, then pour in the hot brine; let cool completely. Cover and refrigerate overnight or up to 1 week.