Go to the Recipe: Grilled Tomato Vinaigrette
You could use a torch, a gas burner (I'd lay down some foil on your stovetop to catch any tomato juices, and set the tomato on a wire rack), or your oven's broiler.
I live in an apartment so no grill. Can I char the tomatoes with a torch?
Use what ever vinegar you would prefer the flavor of.
Can I replace the sherry vinager?
The immersion blender will leave you with an about 90% emulsion that will hold. The tomato is the binder here but the slow addition of oil also helps to emulsify the mix. For a fully emulsified dressing you can use a high speed blender and slowly drizzle in the oil. Either way you want to shake or stir dressing before use.
Will this stay emulsified or what is the binder? Does tomato do this naturally?