Add the sauerkraut, mustard and garlic to a medium pot and heat over medium. Cook, stirring often to warm the kraut thoroughly and once the garlic is aromatic, about 5 minutes, add the asparagus and white parts of the scallion. Keep cooking, stirring often until the asparagus crisp-tender and the scallion whites are slightly softened, about 5 to 7 minutes. Turn off the heat. Transfer to a serving bowl.
Heat 2 tablespoons of canola oil in a grill pan over medium-high heat, toggle the pan to scoot the oil over and across the grates. Once hot, in batch, place slices of the ciabatta bread into the pan and toast until golden brown, crunchy on the outside yet still soft in the middle, about 3 minutes per side. Repeat with 2 more tables of oil and the remaining ciabatta slices. Transfer to a serving platter.
Drizzle the remaining 1 tablespoon canola oil over the hot grill pan and place the chicken sausages on the pan and heat, turning every occasionally until evenly browned and hot all the way through, about 8 to 10 minutes. Transfer to a serving platter.
To serve, fold in the scallion greens, chopped parsley and dill into the kraut and transfer to plates with the sausages, grilled bread and whole grain and Dijon mustard alongside.