1.Prepare the flavoring. If using the Oaxacan pasilla chile, toast it on both sides in a small ungreased skillet over medium heat until the kitchen fills with its smoky aroma. Cover with hot tap water and allow to rehydrate for about 20 minutes. If using canned chipotle chiles, simply remove them from their canning liquid and place in a blender. In a small skillet over medium heat, roast the garlic, turning regularly, until soft and blotchy black in spots, 10 to 15 minutes. Cool and peel.
Drain the Oaxacan pasilla chile and place in the blender, along with the garlic, piloncillo (or brown sugar), grapefruit juice and 1 teaspoon salt. Blend until smooth. Pour in a bowl.
2. Finishing the ceviche. To the flavoring, add the fruit, onion and the jícama. Stir in the shrimp. Taste and season with salt, usually about ½ teaspoon. You can refrigerate your ceviche for an hour or so before serving, or scoop it into small dishes or martini glasses and enjoy right away.
