Thinly slice the zucchini and red onion (a mandoline works great if you have one).
Place the vegetables in a colander set over a bowl to collect the liquid. Add the salt and toss well.
Set a plate on top of the vegetables, add a weight, and leave to drain for 20 to 30 minutes. The heavier the weight, the quicker they release their water.
Measure the collected liquid (you should have around 200 ml / about 3/4 cup). If you have less, top it up with a little water.
Whisk both flours into the liquid until you have a smooth batter. Add a drizzle of olive oil.
Add the drained zucchini and onion and mix until everything is well coated.
Generously oil a non-stick baking tray, approximately 30 x 30 cm (12 x 12 inches). Spread the mixture evenly over the tray.
Drizzle with more olive oil and sprinkle with breadcrumbs if you want an extra crispy finish.
Bake in a preheated oven at 220 C (425 F) for 30 to 35 minutes, until golden and crispy.
A thin, crispy Tuscan zucchini tart that is mostly hands-off: total time about 1 hour, serves 4. Type 1 flour is a lightly refined Italian soft-wheat flour; plain all-purpose flour works as a substitute. Recipe from Valentina Maria (@thatoneitalianchef) on Instagram.
