How to Make It
Light a grill. Skewer each onion slice with a toothpick. Thread the jalapeños on a skewer. Brush the onions and jalapeños with olive oil and grill over a hot fire until charred but still slightly crisp, about 10 minutes. Remove the toothpicks and skewer. Coarsely chop the onions. Peel and chop the jalapeños.
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.
Grill the sausages over a medium-high fire until golden and cooked through, 10 to 12 minutes. Serve the sausages with the grilled-onion chowchow.
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.