To prepare the pepper relish, in a saucepan over high heat, bring the water to a boil. Remove from the heat, add the bell peppers and let steep for 5 minutes. Drain the peppers through fine-mesh sieve, discarding the water.

In the same saucepan over medium-high heat, combine the vinegar, granulated sugar, mustard seeds, salt and celery seeds and bring to a boil, stirring to dissolve the sugar and salt. Add bell peppers and simmer, stirring occasionally, until the liquid is almost evaporated, 15 to 20 minutes. 

Transfer the relish to a storage container and let cool slightly, then cover and refrigerate until completely chilled before serving.

In a wide sauté pan, combine the tomatoes, vinegar, wine, brown sugar, salt and pepper and simmer, stirring occasionally, until a thick, jam-like mixture forms and the liquid evaporates, 20 to 25 minutes. 

Transfer the mixture to a blender or food processor and puree until smooth. Strain twice through a fine-mesh sieve, then stir in the Worcestershire. Cover and refrigerate until ready to serve.

In a large, heavy soup pot, Dutch oven or sauté pan over medium heat, warm the olive oil. Add the onions, season with salt and pepper and cook, stirring occasionally, until the onions begin to soften.

Add the thyme and garlic, stirring to scrape up any browned bits, and cook, stirring occasionally, until the onions begin to stick to the bottom of the pot, about 20 minutes.

Add 1/4 cup of the wine and cook, stirring, until the wine is evaporated and the onions begin to stick to the bottom of the pot. Add 1/4 cup of the wine and cook until evaporated, then add the remaining 1/4 cup wine. Continue to cook, adding 1/4 cup water if the onions begin to stick to the pot again, until they are very soft and deep golden brown. Season with salt and pepper.

Grill the sausages or cook in a fry pan on the stovetop. Serve the sausages with the caramelized onions, pepper relish and Zin ketchup.

NOTE: Caggiano smoked duck sausages are available online, or call the company directly.