2 sweet onions, sliced 1/2 inch thick
Extra-virgin olive oil, for brushing
1/2 cup cider vinegar
1/4 cup plus 2 tablespoons light brown sugar
1/4 cup grainy mustard
1/4 cup Dijon mustard
1/4 teaspoon caraway seeds
1/4 teaspoon turmeric
1 teaspoon cornstarch dissolved in 2 teaspoons water
Salt and freshly ground pepper
3 pounds mixed sausages (see Tip)
1 . Light a grill or the oven boiler to medium high . Skewer each onion slice with a toothpick. Thread the jalapeños on a skewer. Brush the onions and jalapeños with olive oil and on grill or oven boiler on a medium fire until charred but still slightly crisp, about 10 minutes. Remove the toothpicks and skewer. Coarsely chop the onions. Peel and chop the jalapeños.
2 . In a medium saucepan, combine the cider vinegar with the light brown sugar, grainy and Dijon mustards, caraway seeds and turmeric and bring to a simmer. Add the onions and jalapeños and cook over moderate heat, stirring frequently, until the liquid is slightly reduced, about 12 minutes. Stir the cornstarch mixture, add it to the onions and cook, stirring occasionally, until slightly thickened, about 2 minutes. Season with salt and pepper.
3 . Grill the sausages over a medium-high fire on grill or oven until golden and cooked through, 10 to 12 minutes. Serve the sausages with the grilled-onion chowchow.
The chowchow can be refrigerated for up to 1 week.
The sausages can include Italian fennel, merguez, turkey and chicken sausages, which will cook in about 12 minutes; and andouille and kielbasa sausages, which will cook in about 10 minutes.