What are your tips for the best crust? One tip from the sourdough rumour mill suggested that using a casserole dish works particularly well.

Baking dough in a casserole dish with the lid on produces lovely bread with a thin, crispy crust and a moist crumb (that's the inside bit). Inside the dish, the dough expands quickly and the liquid that evaporates during this process is trapped as steam – keeping the dough moist for the first few minutes of baking. Once the crust has formed, no more steam comes out of the dough but that initial hot and steamy baking atmosphere give you a loaf that is moist on the inside and has a thin, crispy crust.

Is there a 'proper' cycle of feeding and fermenting? What would you say is the ideal timeframe for a beginner trying sourdough for the first time?

Once again, there is no single way to do anything. The 'feeding' or 'refreshing' time frame depends if you keep your sourdough starter in the fridge and let it go dormant between bakes or if you feed it every day and keep it at room temperature. The longer the dough ferments (or rises) the better it is for your health (because it is easier to digest) and the more acidic the bread will taste. However, it is possible to over-ferment dough – you will know when you do it because it will be impossible to shape or it will collapse in the oven (ugly, but still delicious). Beginners may want to follow recipe instructions to the letter to get some experience and confidence. Once you figure out that there is actually quite a lot of freedom to baking, you can begin to experiment with 'retarding' your dough (putting it in the fridge to rise slowly) or building it over a few days to change the flavour and texture.

We've heard mixed feedback on how much flour quality has an impact on the bread. Is expensive flour a worthy investment?

Yes. As long as you are getting a quality product! Organically grown, stone-ground flour is better for your health. It is more nutritious, it does not have the long list of additives that most industrially processed flour has, and because it is more gently processed, it does not have the nutrient loss that industrially processed flours experience. It also tastes much better. We forget that flour has a flavour and different kinds of flour grown from different strains of grain and milled in different ways will taste different. It’s clear to almost everyone that a Granny Smith apple is completely different from a Cox Pippin or that cheddar cheese from one producer is completely different from cheddar cheese from another producer. Flour is no different. The better the flour, the better the bread.

What are the characteristics of a really good sourdough and how can one tell an imposter which has been made with a sourdough flavour powder or paste?

The sourdough powders and pastes are so advanced that it can be hard to know whether bread is a 'pure' sourdough or is 'regular bread made with yeast' and the addition of sourdough paste or powder to flavour it. The best thing to do is to buy bread from a baker – rather than from a bakery. The baker will tell you what is in the bread. The person working in the bakery (or at the bread counter in a supermarket) may not know. When ordering bread at a restaurant, ask the waiter where they buy their bread and whether they can tell you anything about it. If the answer is 'no' and 'no' and you are dedicated to eating pure sourdough for whatever reason, don’t eat the bread because it’s unlikely to be made without added yeast.