In the same skillet on medium high heat, add the olive oil. Once the oil is hot, add the onions, bell peppers, jalapenos, and garlic cloves. Saute until lightly golden and soft. Now add in the diced tomatoes and mix everything together. Finally, mix in the Italian seasoning and brown sugar. Transfer the chunky sauce to a mixing bowl and use an immersion blender to puree the sauce. *Alternatively, wait until the chunky sauce has cooled down then use a blender to puree the sauce.