Place the oil and onions into a large nonstick pan and heat on low. Add the salt and pepper and cook for 50-60 minutes, or until soft and golden. They should not brown. Once the onions are caramelized, add the balsamic vinegar. Stir to lift any remaining sugars and remove from the heat. Set aside and freeze any leftovers that remain after filling the pasties.
Spelt Coconut Oil Pastry
Place the flour, sugar, and salt into the bowl of a food processor with the blade attachment. Pulse until combined. Add the coconut oil and pulse until sandy, then add the water a tablespoon at a time, pulsing between each addition. The finished pastry should be a little crumbly looking but come together easily when pressed.
Form a disc with the pastry and wrap it in something to keep the moisture in (I like beeswax wrap). Set it aside, at room temperature, while you prepare the filling.
Pasty Filling
Heat the oil in a large pan over medium heat. Add the leek and cook for 5 minutes, stirring occasionally, until browned and softened. Stir in the salt, pepper, and lemon juice. Add the beans, onion, and peas, and stir to combine. Set aside.
Preheat the oven to 180C / 350F and line a baking sheet with parchment paper. Roll the pastry out on a floured surface to about 5mm and cut large rounds, about 15cm**. Place a tablespoon of hummus on each round and top with a couple tablespoons of the pastry filling. Repeat, rolling out any leftover pastry, until it's been used up.
To close the pastries, use a finger or brush to slightly dampen the outer ring of the pastry round. Pinch each pastry closed, starting at one corner and moving around to the other. Use a fork to crimp the edge and seal the pasty. If it tears slightly don't worry, it shouldn't open up much in the oven. Brush the pasties with an egg wash if desired to help with browning. Continue until all the pasties are sealed, then place them on the prepared baking sheet and bake for 20-25 minutes, until crisp. Serve hot or keep leftovers in a sealed container for up to 2 days.
Notes
• Freeze unbaked pasties in a well-sealed container and bake from frozen if you don't want to make the whole batch.
• I used an egg-wash on the outside of the pasties, but it's not about taste, just appearance. Adding an egg wash makes them golden, and not including it will result in a slightly lighter pastry.
* I make this pastry with a mix of different spelt flours. Here I did half whole and half light, but it works well with fully light and whole spelt as well. Avoid bread flour.
** I used a cereal bowl to make the round imprints in the pastry and then cut them out with a butterknife. If you've been blessed with a nice pastry cutter, and you can use that instead.