fresh mozzarella or boccoccini
good quality olive oil
salt and pepper, to taste
My preference is to use Saputo's mozzafina di latte cheese. I can't find a link to it, but I buy it at Costco. But I'll use boccoccini when I haven't had time to get to Costco. I use our Olive & Olives' organic extra-virgin olive oil and recently, have been using a cider balsamic vinegar from Verger Pierre Gingras that I picked up when we were in Rougemont last year doing a cider tour.
You basically just slice the tomatoes, sprinkle them with a bit of salt and pepper and then pour a bit of olive oil and balsamic vinegar on them. My preference is to load mine with vinegar, as you'll see in the photo... mmm... my mouth is watering as I write this. I have a thing for vinegar. Perhaps it dates back to when I was much younger and someone told me that if you put vinegar on your gravy (when eating fries), it takes the fat out of the vinegar. That's clearly not true, though I believed it at the time and got into the habit of putting vinegar into gravy (I know! Sounds gross, but it's great - even with poutine!). Anyhow, that's just a side-story of why I put so much vinegar on mine. Enjoy your tomatoes :)