Acquire lots of delicious tomatoes. These are from a box of fabulous heirloom tomatoes from Wild Boar Farms
at my local farmers' market. Because I'm cheap I got a box of seconds, meaning that they taste just as good but are aesthetically imperfect or got dinged in transit or handling sometime today. The squished/dinged/leaky tomatoes need to be used immediately to avoid spoilage.
Chop small tomatoes in half, and slice larger tomatoes in thirds or quarters. Lightly coat your baking dish in oil; I use spray canola for this part because I'm lazy and these heirloom tomatoes carry so much liquid they don't need more oil on the bottom.
Place your tomatoes in a single layer in the baking dish, then drizzle with extra virgin olive oil. Sprinkle with salt, pepper, and spices; here I used chopped fresh rosemary and dried oregano. Optional: stick garlic cloves in any remaining spaces to roast and do some serious flavor-trading.
Important storage notes: refrigeration kills off proper tomato flavor. Keep them on your counter, and check daily for softness or incipient mold. Don't wash them until you're ready to use them.