Preheat oven to 200 °C or 180 °C fan bake. Spray a baking dish with oil spray.
Make quiche
Peel and finely dice 1 brown onioninely chop 2 broccoli. Drain 400 g corn kernels. In a large bowl, whisk together ¾ cup flour, 1 tsp baking powder and season with salt and pepper. Add 6 eggs and ¾ cup milk and whisk thoroughly to combine. Crumble in 100 g feta cheese and add onion, broccoli and corn. Mix until combined.
Bake quiche
Transfer the mixture to the baking dish and grate ½ cup cheese over top. Bake for 35-40 minutes, until golden and cooked through. Tip: To check if the quiche is cooked, poke the middle with a skewer or the tip of a knife. If it is cooked, it should come out clean.
Make salad
Peel and grate 1 beetroot, then add to a large bowl with 2 cups mixed salad leaves, 2 tsps balsamic vinegar and 1 tbsp olive oil. Toss all salad ingredients together and season with salt and pepper. Sprinkle ¼ cup slivered almonds over top.
To serve
Allow the quiche to cool slightly before slicing. Serve the cheesy veggie quiche with the fresh garden salad on the side and tomato sauce.