In a large skillet with a lid, warm 1 tablespoon oil over medium/medium-high heat. Add the sausage and cook until browned on both sides, about 2-3 minutes per side. Transfer to a plate.
To the skillet over medium heat, add the remaining 1 tablespoon oil along with the cabbage, onion, garlic, thyme, ½ teaspoon salt, and pepper. Cook for 3-5 minutes or until softened, stirring occasionally.
In a liquid measuring cup, mix together the water, mustard, soy sauce, and vinegar. To the skillet, stir in the chickpeas and remaining ½ teaspoon salt. Reduce the heat to low, pour the liquid in, and give the pan a shake to distribute the liquid.
Nestle the sausages into the skillet so they are sitting in the liquid (don’t just plop them on top). Cover and simmer over medium-low heat for about 10-12 minutes or until sausages are cooked through.
Use a fork to mash up some of the chickpeas, if you’d like. Serve the chickpeas topped with sausage and spoon any liquid from the skillet over top. Top with a dollop of sour cream (if using), plenty of herbs and black pepper. If you want more mustardy flavor, you can put more on the side or put a little dollop on top.