Bring a pot of water to the boil then cook potato for 12 - 15 minutes until very soft.

Drain, mash and set aside.

Sizzling spices: Heat oil in a dutch oven or pot over high heat. Add black mustard seeds, cumin and fennel seeds. Let them sizzle for 15 seconds - careful, they might pop!

Curry leaves: Then add curry leaves and stir for 15 seconds.

Aromatics: Add garlic, ginger and onion. Cook for 4 to 5 minutes until onion is tinged with gold.

Tomato: Add tomato paste and tomato, cook for 30 seconds.

Spices: Add curry powder, turmeric and chilli. Cook for 30 seconds.

Most Veg: Add zucchini, carrot and cauliflower. Stir well to coat in the spice paste.

Water: Add water, salt and pepper. Stir, bring to a simmer then put the lid on and reduce heat to medium low (so it's simmer gently).

Cook & reduce: Cook for 15 minutes until vegetables are soft. Then remove lid and simmer for 5 minutes to reduce liquid a bit.

Add mash: Remove from stove. Add peas and potato, mix through well.

Taste: Taste and add more salt and pepper if needed.

Cool: Place lid on and cool for at least 30 minutes (even overnight is fine).

Preheat oven to 180°C/350°F (all oven types).

Grease a large pie dish with butter, or oil spray (Note 6). Drape in a puff pastry sheet.(I don't blind bake here - see Note 5)

Fill with Filling - slightly mounded is fine.

Fold in the corners of the puff pastry sheet.

Top with puff pastry sheet - turn 90 degrees to the base puff pastry sheet (see photo).

Fold the overhang puff pastry under itself - no need to be neat here, this is a rustic pie!

Egg wash: Brush with egg, cut a 2cm / 1" cross in the middle (to let steam escape).

Bake 50 to 60 minutes, until the top is very deep golden and flaky.

Stand 5 minutes then slice to serve. A dollop of plain yogurt goes well with this!