Here's what I did (which was not entirely successful, so see below for future adjustments):
3.25 C all-purpose flour (for GF flour types and quantities, see original recipe)
1.5 tsp baking soda
0.5 tsp sea salt
.67 C canola oil
1.5 C lapsang souchong (boil 1.5 C water, let sit 3 minutes, steep with 1 level tsp loose tea leaves for 5 minutes--brewed to drinking strength, in other words)
2 tsp vanilla extract
1.5 C maple syrup
Mix dry, mix wet, add wet to dry, mix until just combined. Bake in parchment-lined loaf pan at 375F to internal temp of 212F.
Results and modifications:
* The original recipe calls for an 8.5" loaf pan. I filled mine and it looked ready to overflow, so I transferred the batter into my 9.25" pan to be on the safe side.
* It needed to bake for 1.5 hours, way longer than I was expecting--especially given that I used a larger pan than the one called for--and the top and bottom scorched a bit. I blame the guesswork of converting between wheat and GF flours. The batter also seemed quite wet to me. Possible ways to try to get around this:
-- use only one cup of tea (brewed with the same amount of tea leaves)
-- bake it at 350F
-- divide the batter between two smaller loaf pans
-- use a square or round cake pan
For the next iteration I'll probably break out my lovely 9" round springform pan. The batter could even be divided into two square or round pans, baked, and then layered with an appropriate filling; I'd suggest orange marmalade for the original Earl Grey recipe, or if you want to be really daring, a sea salt and black pepper vegan buttercream for the lapsang souchong version. (Has anyone tried the buttercream recipes in Quick and Easy Vegan Bake Sale or VCTOTW? I'm skeptical of anything that calls for shortening but would love to find one that really works, especially since I cannot find salt-free vegan butter anywhere.)
* Regardless of modifications, USE THE THERMOMETER. Going by my nose, I would have taken the cake out of the oven nearly half an hour before it was actually baked through. Going by the thermometer, the outside is slightly scorched (bah), but the middle is perfect.
* The cake is quite dense, almost heavy. I suspect the lapsang isn't as acidic as the Earl Grey, so I might change to 1 tsp baking powder and .5 tsp baking soda, and/or add a splash of cider vinegar.
* Once I get the burnt crust out of the way and dig into the middle of the cake, I can really taste both the maple and the lapsang! Delicious. I don't think it needs to be smokier, but you could go up to 1.5 tsp tea leaves (or one heaping teaspoon) if you want more intense flavor. It is quite sweet, but not cloying.
Time to buy more maple syrup and see if I can make a version that works!