Cut the cap off each pepper and pull out pith and seeds. Cut into 1/2" strips. Lay skin side up on a baking sheet.
Drizzle peppers with olive oil and broil for about 10 minutes, until skins are charred black.
Remove from oven and use tongs to place peppers into a glass bowl. Cover with foil and allow to steam in bowl for about 10 minutes. Remove foil covering and peel charred skins off.
Pulse almonds and sesame seeds in a food processor until finely chopped. Add roasted red peppers, chipotle peppers and sherry vinegar. Purée until well combined. Season mole sauce with salt and pepper to taste and set aside.
Lightly brush grates with oil and preheat grill to about 400 degrees F. Place short ribs on grill and cover while watching for flare ups. Turn short ribs occasionally until charred on all sides and desired doneness.
Transfer ribs to cutting board and let rest 10 minutes. Thinly slice ribs against the grain and serve immediately with mole sauce.