Cut the pork schnitzel into thin strips, roughly 1/4 inch thick.
Season the pork strips with salt, pepper, hot paprika powder, thyme, marjoram, and oregano.
Heat a large pan on medium-high heat and pan-fry the pork strips for 5-6 minutes, stirring occasionally, until cooked through to an internal temperature of 63°C / 145°F.
Transfer the cooked pork to a plate.
Cut the colored peppers into thin strips. Cut the onions into thin strips. Mince the garlic cloves. Slice the mushrooms.
In the same pan on medium heat, add the peppers, onions, and mushrooms. Cook for 5 minutes, stirring occasionally, until vegetables are tender but still crisp.
Add the minced garlic and cook for 1 minute, stirring constantly.
Return the pork to the pan. Add the sour cream and spicy mustard, stirring well to combine.
Reduce heat to medium-low and simmer for 5 minutes, stirring occasionally.
Taste and adjust seasoning with salt and pepper if needed.