Making the sweet and spicy giardiniera: Combine all the gardiniera ingredients in a large, clean bowl and toss to mix. Fill 2 large, clean mason jars with this mixture. (Not enough liquid to cover the vegetables? Just top off the jars with a little more vinegar.) Close the lids tightly, and store in the fridge for 2 days before serving.
Making the sausages: Heat the olive oil in a saute pan over medium heat. Stab several holes in each sausage with a fork. Turn the heat down to medium-low, and add the sausages to the pan. Cook for 20 minutes, turning every 4 minutes.
Slice the baguette lengthwise and divide into four segments. Toast the baguette. Add the bocconcini slices and a sausage to each segment. Garnish generously with the giardiniera.