Add warm water (1½ cup), active dry yeast (1½ tsp / 6g), and a dash of sugar to the mixing bowl (of a stand mixer). Let stand for about 5 minutes while you continue the other steps.(If using a different type of yeast, follow the instructions on the container. The main difference is usually just whether you have to activate it in water or not.)
In a separate bowl, combine all dry ingredients: GF flour (440g), xanthan gum (18g), sugar (60g), and salt (21g). Gently stir just a little bit to incorporate the ingredients together. (Xanthan gum has a tendency to "poof" into the air when disturbed.)
Add dry ingredients to the water & yeast mixture in the mixing bowl (which should be bubbling/foamy).
Add oil (1 Tbsp) to the mixture.
Start up the stand mixer, beginning on the lowest speed to avoid kicking up a cloud of flour. Then crank it up a notch or two.(This isn’t as precise a process as mixing wheat dough, where you have to use a light touch to avoid overworking the dough, not to mention the mixer itself.)
As needed, pause the mixer to scrape the sides of the bowl and the beater with a rubber spatula dipped in water. Repeat until everything looks sufficiently combined.(I usually keep a small bowl of water for dipping throughout the process; you’ll need it in the next few steps as well.)
Grease the bread pan with a stick of vegan butter (preferred) or oil spray. Use a paper towl to wipe it so it’s not overly wet.
Use the rubber spatula to add the dough to the pan. You don’t have to do it all in one shot, and in fact it can be helpful to do it a little at a time to help with shaping the dough. It may also be helpful to dip the spatula in water each time you use it, to keep the dough from sticking to it. The water may also help you to shape the dough and make it look pretty, if you feel the need.
Lightly spray some plastic wrap with oil and cover the pan.
Rest
Let it rise for 2-3 hours in a warm, dark place.(If you can't figure out a warm, dark place, just turn your oven on at its lowest setting for a minute or two.)
Bake
Assuming the dough has puffed up significantly by now, pre-heat the oven to 425 F.
If desired, "score" the the bread by lightly dragging the tip of a sharp knife across the top of the loaf.
Bake for 25-30 minutes. You’ll know it’s done when the top is looking significantly browned, just to the point of looking like it might start to get burned.
Remove from the oven. You could turn it out onto a cooling rack immediately, or you could wait a little longer. As noted above, the outside does tend to brown easily, so you may favor giving the inside a little more time in the moderate heat to dry out. Some actually recommend leaving it in the oven, turned off, with the door open as the heat dissipates. Since I have toddlers, I’ve opted to, uh, not do that. But you could leave it in the pan for about 15 minutes for a similar effect. I wouldn’t go much longer than that, though, because it could start to get a soggy bottom.
Let it cool as long as you can before slicing it, as gluten-free dough tends to be gummy for a while after baking. If it’s allowed to cool down longer, it will have a more bread-y texture.