Chop the onion and red bell pepper. Mince the garlic.
Heat a large pot on medium heat.
Place olive oil into pan.
Once heated (thin and shiny in texture), add onion. Season with salt and pepper. Cook, stirring occasionally until translucent, approximately 4-5 minutes.
Add red bell pepper and cook until soft, approximately 4-5 minutes.
Add garlic and herbs (thyme, tarragon, basil and oregano) and cook, stirring for 30 seconds, until fragrant.
Add crushed tomatoes and allow to boil, stirring occasionally. Reduce heat to medium low and simmer for 15-20 minutes.
Add balsamic vinegar. Season with salt and pepper.
Using an immersion blender, blend until smooth. (Alternatively, place sauce into standing blender and carefully blend).
If completing entire dish in one day, continue to below step. If to be completed at a separate time, store in the refrigerator in an air tight container.