Preheat the oven to 225°F (110°C). Halve the tomatoes lengthwise.
Place the tomatoes cut-side up in a single layer on a rimmed baking sheet or shallow roasting pan. Nestle the garlic and herbs between them, drizzle olive oil generously over everything, and season with salt and pepper.
Roast uncovered for 10–12 hours, rotating the pan once halfway through. The tomatoes should shrink by about 70%, look wrinkled but still supple, and sit in rich, ruby oil.
If the edges darken too fast, tent loosely with foil.
Serve with fresh mozzarella and basil, or spoon on top of anything.
