In a food processor, blend oats until the texture of coarse sand. Add sunflower seeds, garlic powder and salt and blend until the seeds are also a crumb-like texture. Add the coconut oil and pulse until well incorporated.
Add water, 1 tablespoon at a time, pulsing until the mixture comes together in a ball. It should take about 3 tablespoons until this happens.
Pour the dough out into the tart pan and use your fingers to press in the crust firmly. Use a fork to prick the crust 15 times to allow steam to escape when baking.
Meanwhile, use clean paper towels to dab away moisture from the tops of the tomatoes. Transfer tomato slices onto two baking sheets lined with parchment paper. Brush tops with 1 tablespoon of olive oil.
Place the tomatoes in the oven, and bake for 45 minutes until they begin to dry and wrinkle. Once the tomatoes go into the oven, add in the tart crust to bake at the same time. Bake the tart crust for 30 minutes, then remove and allow it to cool while the tomatoes finish roasting.
Add all the filling ingredients to your food processor then blitz until smooth and creamy. The consistency will be about like thick hummus.
Once the tart crust has cooled for the 15 minutes or so that the tomatoes have continued roasting, transfer the filling into the tart shell.
Carefully spread the filling mixture across the bottom of the tart as it will lift the crust if you spread too much sideways.
Arrange the roasted tomato slices on top. Press in a little.
Brush with olive oil and dust with a sprinkle of sea salt and herbs.
Return to the oven and bake for 30 minutes (until the crust is a little dry-looking at the edges, the filling has pulled away from the edges of the pan and the tomatoes are cooked and settled into a layer). Remove from the oven and allow to cool. Run a knife around the edge to separate the filling from the sides of the pan, if needed, before lifting the springform insert from the pan.
Sprinkle on fresh chives, basil & oregano, or other herbs you have. Serve with a big salad or dips and fresh vegetables.
This tart is best fresh, but can be warmed up in the microwave the next day. After that, the topping gets soggy from the moisture of the tomatoes, though no flavor is lost.