If you don't want to use a blender: Finely dice 3 tablespoons of sweet onion. Add onion, vinegar, olive oil, honey, dijon mustard, and spices to a small bowl. Whisk until fully emulsified.
If you want to use an immersion blender: Add roughly chopped sweet onion, vinegar, olive oil, honey, dijon mustard, and spices to a tall cylinder container (like a mason jar). Blend on high with an immersion blender for 20-30 seconds until fully emulsified.
If you want to use a standard blender: Add roughly chopped sweet onion, vinegar, olive oil, honey, dijon mustard, and spices to blender. Blend on high for 20-30 seconds until fully emulsified.