Place the yeast, sugar and ½ cup of water in the bowl of a stand mixer or a large bowl and let it stand five minutes until frothy.
Sift in 3 cups of flour and baking soda. Add salt. Drizzle in the water as needed and knead until the dough comes together.
Add 3 tablespoon of oil and knead on medium-high speed until all of the oil is absorbed by the dough. This will take a little more effort if doing by hand, but you'll get there. I find that after adding the oil the dough tends to get a little sticky again, so I usually add a little more flour until it comes together in a ball.
Stop kneading at this point and turn the dough out onto a work surface. Fashion it into a smooth ball, and place in an oiled bowl. Turn over once to coat the top of the dough with the oil, cover with a kitchen towel, and let the dough rise in a warm place for an hour or until doubled.
While the dough is rising, you can caramelize the onions. Heat the remaining 1 tablespoon of oil in a skillet, add the sliced onions and about ½ teaspoon salt. Cook over medium-low heat, stirring frequently, until the onions are a nice golden-brown. You can also add a pinch of sugar to make the onions brown faster. Let the onions cool.
Oil the baking pan or the muffin tin.
After the dough has risen for an hour, turn it out onto a lightly floured work surface. Punch the dough down and, using your hands or a rolling pin, shape it into a rectangle about 12 inches long and nine inches wide.
Sprinkle the caramelized or raw onions, whichever you're using, evenly over the rectangle, leaving a 1-inch border on the top and bottom.
Sprinkle the poppy seeds over the onions evenly.
Dampen the long edge of the dough that's away from you and then gently roll up the dough as tightly as you possibly can, the way you would a jelly roll or a cinnamon roll.
Press the seam in to form a seal. Using a sharp knife, cut into 12 rolls.
Place the rolls, evenly spaced, in the baking pan. Or, if using a muffin pan, place one roll in each of the tins.
Let the rolls rise for another hour, again in a warm place. If you want a golden-brown look for your rolls, brush the tops with 1 teaspoon maple syrup mixed with 1 tablespoon oil before placing them in the oven.
In the last few minutes of the second rise, preheat the oven to 350 degrees. Bake the rolls in the oven for 30 minutes.
Remove to a rack and, when you're able to handle, get them out of the muffin tins or pull them apart from the baking pan. Enjoy.