In a large saucepan, heat a drizzle of oil on medium.
Add onion and saute for 3 to 5 minutes, or until softened.
Add cabbage, water, vinegar, sugar. Let simmer on low 30 minutes, stirring occasionally. Salt and pepper to taste, and remove from heat.
After cabbage has cooked for about 10 minutes, start cooking the sausages.
In a high sided saute pan, add brats and beer. Add just enough water to help cover the brats.
Bring to a boil, then reduce heat to low and let simmer for 10 minutes.
Drain the liquid, then add a drizzle of oil to the pan and turn the heat up to medium. Brown the brats on all sides until their internal temperature is 165°F, then turn off the heat and remove them from the pan. Place them on a plate, covered with aluminum foil to keep them warm.
Return heat to medium and add another drizzle of oil to the pan. Once hot, add rest of the onion and saute for 3 minutes until they start to soften.
Add bell peppers and cook for another few minutes until both onions and pepper are softened. Add garlic, oregano, smoked paprika, red pepper flakes and cumin, and cook another 30 seconds, until fragrant. Salt and pepper to taste.
Add prepared cabbage to pan (sans liquid) and carefully stir to combine. Add sausages back to the pan, cover, and heat until sausages are warmed.