Hearth Haggerty: the recipe

Here is the recipe for Hearth Haggerty. As Zillah said, there have been through several iterations before we arrived at this version, so please experiment with substituting your local cheese, or your favourite dough or herbs, and tell us about the results. If anything needs clarifying, just ask.
 
Ingredients
305g Wholemeal Rye Leaven (See Notes: Leaven)
345g Warm water (about 115 boiling to 230 cold)
100g Plain white flour
100g Wholemeal rye flour
240g Strong white flour
10g Salt
Sunflower Oil (See Notes: Oil)
2 Onions (medium to large)
250g Anster Cheese
20 Sage leaves (See Notes: Sage)
Ground Pepper.

Method:

Disperse the leaven in the water. Mix together the flours and salt. Add the flour and salt mix to the leaven and water and mix together until you have a very soft, sticky, dough. Cover the bowl with clingfilm or a plastic bag and leave to stand for 20 minutes. Mine looks like this at this point:

Oil your hands and stretch the dough: slide your fingers under one side of it and lift it gently, letting its own weight stretch it, and fold it back onto itself:

The aim is to stretch it without letting the gluten tear. Repeat this action every ten minutes for one hour, by which time you should start to feel some tension [but see Notes: temperature and timings]. Then do it every twenty minutes for second hour. Then let it sit for a third hour, by which time it should have expanded a fair bit and have a fragile, souffle-esque feel in the hand:

During the third hour, slice the onions and gently fry them until the are very soft, have taken on a light tan colour, and have little or no moisture remaining. Chop or crumble the cheese into small pieces and finely chop the sage.

Grease a baking sheet of 36cmx26cm or an equivalent area with butter or lard (see Notes: oil and fat), and smear some sunflower oil on top of the grease.

Tip your dough out onto the baking sheet, divide it in half and put half back in the bowl. Press and stretch the remaining half out to cover the sheet. Spread the onions over the dough, sprinkle the sage evenly over the onions, add a uniform grinding of pepper and distribute the cheese:

The next step is a bit of a challenge for your dough handling skills: with oily hands, pick up the second half of the dough and, without letting it touch anything, use a series of smooth, quick motions to form it into a thin sheet and lay it over the cheese [See Notes: Dough handling].

Let it sit for two or three hours, until has puffed up a bit. Then press it down with your finger tips all over and bake on a stone in an oven preheated to 240 celcius for about 30 minutes.

Take it out of the oven, and transfer from the baking sheet to a wire rack to cool. If you can, leave it for about 30 minutes before you cut into it.

Notes:
Temperature and timings: Our kitchen is usually around 17 or 18 degrees (celcius) at this time of year. If yours is warmer, your timings will be shorter than mine are here. If it is colder they will be longer. There is inevitably a bit of feeling your way in getting a new recipe to work in your own environment.
Leaven: If you don't have a leaven, there are excellent instructions in Dan Lepard's book 'The Handmade Loaf' and in Andrew Whitley's 'Bread Matters', and in many others, and on the web. It takes about a week. Alternatively, if you live near here (Dunfermline, Fife), I'd be delighted to give you some of ours.
Oil and Fat: You can end up using quite a bit of oil in this recipe. I think it may be possible to overdo it, which can lead to a very slight bitterness. Zillah disagrees. In any case, it is intended to be an oily bread. However, if you want to reduce the amount of oil I suggest that to stop your hands sticking too much whilst handling the dough, you dip them in water instead. I'd also like to encourage you to use the best quality oil you can find, by which I mean a) organic and b) cold-pressed c) produced as near to you as possible. Yes, it's more expensive, but it's worth it. For greasing the baking sheet, you will need to use hard fat, either butter or lard. Pure vegetable oil will be absorbed by the dough and will not prevent sticking. My favourite is pork lard, but to get organic pork lard in the UK, you must buy the fat and render it yourself. It's a bit of a faff, but again, worth it a thousand times over.
Sage: Our sage leaves here in Fife are about 1inch long. If your leaves are bigger, use fewer. Or more, if you like sage a lot.
Dough Handling: Stop laughing, I know it can be done because I've done it. At least twice. I don't really know how to describe what I did though, something like letting the edges slide through your hands whilst gravity does the stretching. To be honest, it ends up as a mess quite often, so here's an alternative method: holding it above the baking sheet, stretch it into a sausage as long as the sheet, and lay it down the middle. Now slide your fingers between it and the cheese layer at one end and stretch it out to the sides. Work your way along until you have covered the whole sheet. If it goes wrong, you can simply smooth it up to the edges, although this can disturb the even distribution of the filling. Don't worry too much about small holes: they will mostly disappear as the dough rises, and a bit of cheese showing through can be quite attractive.