Don't be afraid to mix different starches together. You can use a combination of potato, corn and tapioca starch, or just one of them. Though I do not care for potato starch alone; mix with one other starch. It all depends upon your personal preference.
Baking soda has a bitter taste and is best used with something to counteract the taste such as buttermilk. I used Greek yogurt. When baking with baking soda do not set the dough in the refrigerator or set it aside for later baking, as baking soda begins to rise your dough upon mixing and will not last long.
You can also use baking powder instead of baking soda, but you'll need more. In using baking powder you can always use milk or a milk substitute, but you'll have to play around with the quantities: less milk than yogurt because it is watery; and about 2 - 3 times the amount of baking powder compared to baking powder.
If you wish a really flaky crust don't hesitate to substitute some of the butter for more shortening.
If you are a veteran pie crust baker you probably already know that you can weigh your crust down with a pie crust weight to prevent the crust from rising, but it is a pleasure to see anything rise in gluten-free baking, therefore I let it rise, especially when starting from a 1/8" thick raw dough. If you wish to stick with the thin crust and do not have a pie crust weight you can use uncooked beans, such as white beans, etc.
The color of the custard will be determined by what type of agave and vanilla you use. Non-amber colored agave will give you more of a true custard color and using white powdered or clear liquid vanilla will also help in developing a true color.
Tart pans, also known as quiche pans, come in different varieties. You have your regular metal pan, which does not have removable sides, causing you to leave the tart in the pan while serving; you have the springform pans where you can remove the sides; and you have the porcelain dishes which you also leave the tart in the pan. With the non-springform pan you lose a bit in presentation, but if you are making this for your family you may not care.
The springform pan works great, as you can show off your beautifully fluted crust! I used the latter, a safe bet, a porcelain dish: no mess; no fuss. It also makes for a nice presentation. I used a stainless pie server to scoop it out and it removed very easily without any broken crust.
This recipe takes some time to make. So, if you want to break it up you can peel and slice the peaches in advance. Just make sure you coat them with some lemon juice to prevent browning.
This recipe should not be made in advance, as it doesn't look pretty at all once refrigerated. You may want to consider adding lemon juice to the peaches before adding them to the tart, as this will prevent some browning. I could not do this, as I am allergic to citrus.