Blanch the tomatoes for 5 minutes. Remove the skin, cut each tomato into quarters, and discard the seeds. Arrange the tomatoes in a dish, coat them with Garlic Olive Oil. Season with salt, pepper, and sprinkle with thyme. Bake for 2 hours 30 minutes at 90°C.
Place the tuna in a deep dish, generously coat each steak with Basil Mint Olive Oil. Cover and refrigerate until the tomatoes are finished cooking.
Coat the tomatoes again with Garlic Olive Oil 5 minutes before the end of cooking.
Heat a pan or grill over high heat without fat. Sear the tuna for 2 to 3 minutes on each side. Season with salt and the 5-berry blend.
Serve the tuna immediately with the tomatoes.