In a pan over medium heat, brown the diced sausage on all sides. Once browned, transfer most of the sausage to a separate pot, reserving a few pieces for garnishing later.
In the same pan, add 1 tablespoon of olive oil and sauté the finely diced onion until it becomes translucent. Then incorporate the finely diced garlic and sauté for an additional 2 minutes. Transfer this mixture to the pot with the sausage.
Sauté the diced bell peppers in the pan until they attain some colour but remain firm to the touch. If using, add the diced zucchini and sauté for a few minutes until slightly softened. Transfer the majority to the pot, setting aside a few pieces for garnish.
In the same pan, heat 2 tablespoons of olive oil over medium heat. Add the Hungarian paprika and optional chili flakes, frying briefly for 1-2 minutes to release their fragrant aromas. Be cautious to prevent burning. Once aromatic, transfer this spice mix to the cooking pot.
Add the fresh chopped tomatoes (or canned tomatoes), stock, sugar, and optional marjoram to the pot. Bring the mixture to a boil, then reduce the heat to a simmer. Cover the pot with a lid and let it simmer for 20 minutes, stirring occasionally.
After the initial 20 minutes, remove the lid and continue to simmer for another 20 minutes to reduce the liquid. Stir occasionally to prevent sticking. As the liquid evaporates, the flavors will concentrate and intensify. Taste the dish during this phase and adjust the seasoning as needed, adding more salt, pepper, or spices to suit your preference.
Check for final seasoning adjustments. Serve hot, with a side of sourdough bread or on pasta.