Make the adobo marinade. Heat the oven to 400 degrees and position a rack in the upper third. Scoop the garlic into a small microwave-safe bowl, cover with water and microwave for 1 minute. Tip off the water, then put the garlic into a blender or food processor along with 2/3 cup very hot tap water, the chile powder, cinnamon, pepper, cumin, oregano, vinegar and a scant teaspoon salt. Process until smooth. Scrape half into a large microwave-safe bowl (big enough to hold the chicken or cauliflower) and the rest into a small bowl (for the glaze). Add the chicken (or cauliflower) to the large bowl and use a large spoon, tongs or your hands to toss the chicken (or cauliflower) in the marinade until it is evenly coated.
Roast the chicken and potatoes. Spread out the chicken (or cauliflower) in a single layer onto half of a rimmed baking sheet, leaving some of the adobo in the bowl. Slide into the upper third of the oven and set a timer for 35 minutes (25 minutes for the cauliflower). Immediately scoop the potatoes into the unwashed chicken-marinating bowl, measure in 1 tablespoon water, about a tablespoon of olive oil and a generous ½ teaspoon salt. Mix everything together, cover (if using plastic wrap, poke a couple of holes to let out steam), then microwave at 100% power for 5 minutes, until the potatoes are nearly tender. Remove the baking sheet from the oven, stir the potatoes they’re evenly covered with oil, then spread them on the uncovered side of the baking sheet and return to the oven.
Glaze and serve the chicken and potatoes. Mix the unused adobo with 1 tablespoon olive oil and the honey (or a stand-in). When the timer goes off, remove the baking sheet from the oven and, with a pastry brush, brush the glaze over the chicken (or cauliflower). Return to the oven and cook for 3 or 4 minutes more, until the glaze is set, the internal temperature of the chicken registers about 150 degrees on an instant-read thermometer and the potatoes (and cauliflower) are tender. If time allows before serving, let the chicken rest for a few minutes under a piece of foil to reabsorb its juices; hold the potatoes in a turned-off oven. With a sharp knife, cut crosswise through the chicken breasts and serve one breast piece with a chicken thigh and a portion of the potatoes. Pass the salsa for everyone to spoon on al gusto.