In a 10-inch to 12-inch saute pan over a medium high flame, heat virgin olive oil until smoking. Add onion and garlic clove until softened (about 4 to 5 minutes). Add all the peppers and, shaking regularly, cook until quite soft yet still retaining individual texture (about 10 to 12 minutes). Remove from heat to large mixing bowl and allow to cool.
In a small mixing bowl, combine balsamic vinegar, marjoram and extra virgin olive oil and season with salt and pepper. Pour this blend over now cool pepper mixture and toss gently with hands, being careful not to break up the peppers. Set aside for later use or serve as antipasto.