First make the dough for the pasty.
In a large bowl mix the warm water (just hand warm, not boiling hot) with the agave syrup, olive oil and yeast. Stir. Let it stand for 10 minutes to get the yeast activated, the mixture should start to bubble up.
Next start mixing in the flour. Don’t add all the flour at once, each flour is different and can yield different results at different quantities. After about 1 and half cups add 1 tsp of salt, get your hands in, mix, adding more flour until you get soft pliable dough, not dry or stiff. You are making a basic bread dough.
Invert the dough on a floured surface and knead for 5 minutes until you get a smooth ball of dough. Add more flour if dough is sticking to your surface too much.
Rub a little bit of olive oil all over your ball of dough, place in a large bowl, cover with cling film and let rest in a warm place for about 1 hour or until it has doubled in size.
Preheat your oven to 200 degrees C.
While your dough is rising, peel your sweet potatoes and cut into 1-inch dice, place in a roasting dish lined with some baking paper. Add 1/2 Tbs of olive oil making sure all pieces are coated. Roast in a the oven for about 25 minutes or until the potatoes are cooked through and caramelized along the edges.
In a large frying pan, heat another half a Tbs of olive oil. Add the onion and cook for 5 minutes or until soft.
Add the garlic in and cook for further minute.
Cut the mushroom into 1 centimeter pieces and add to the onion and garlic. Cook for 5 minutes or until mushroom is soft.
Remember to season everything.
Next add in the spinach, cook until it is just wilted, about 1 minute.
Place the vegetables into a bowl together with the roasted sweet potatoes.
Mix all the vegetables together, breaking some of the potatoes as you go. Season with plenty of pepper. Set aside.
When your dough has risen, invert it onto a floured surface and knead for 2 minutes.
Divide the dough into 4 (this makes large, calzone size pasties) or 8 pieces (for smaller pasties). Make sure to divide your vegetable mixture accordingly.
Roll each piece of the dough into a large circle (the dough should be quite thin, like pizza), place the filling on one half of the circle leaving about 1/2-inch border. Fold the other half over trying not to make any holes. Press the edges down with a fork.
Line a baking sheet with baking paper and place the pasties on top. Bake for 25 minutes in a 200 degrees C oven or until the pasties are lightly brown and sound hollow when you tap on the pastry.

Dough
1 cup warm water
1 tablespoon olive oil, plus more for the rising of the dough
1 teaspoon agave nectar syrup
1 sachet of instant (or fast acting) yeast
150 gram (1 cup) fine wholewheat flour
225 gram (1.5 cup) wholewheat spelt flour
salt

Filling
2 medium-large sweet potatoes, roughly 600 gram or 1.5 pound
1 tablespoon olive oil, separated
3 large portobello mushroom
1 medium red onion, finely chopped
3 garlic cloves, very finely chopped
1 teaspoon fresh thyme
200 gram (0.5 pound) baby spinach
salt and pepper to taste