Grate the potato coarsely on the large holes of a box grater or in a food processor using the grating blade. Wrap the grated potatoes in a clean kitchen towel (no fabric softener, please!) and squeeze vigorously to get rid of any excess liquid. Transfer to a large bowl. Do the same with the onion. If you don’t care about staining your dish towel, do the same with the beets. Otherwise, grate the beets and squeeze out the moisture by hand; add to the bowl with the potatoes and onion.
Add the egg, thyme, rosemary, flour, and several twists of pepper and mix thoroughly — your hands are good for this.
Line a plate or tray with paper towels. Fill a large nonstick skillet with vegetable oil to a depth of ¼ inch (6 mm) and heat the oil over medium-high heat. When the oil is hot, stir the salt into the latke mixture, pick up a small handful, and squeeze out even more liquid (depending on the potato and onion you use, you might have quite a lot of liquid).
Shape the mixture into a round, flat patty about 3 inches (7.5 cm) in diameter and carefully add it to the hot oil. Repeat until you have a panful of patties, but with plenty of room between them to flip the latkes. Fry until the latkes are crunchy and slightly browned, about 3 minutes on each side. Transfer to the paper towels to drain. Repeat to form and fry the remaining potato mixture.
Serve at once, with the preserved lemon and yogurt dressing or plain yogurt alongside.
Preserved Lemon and Yogurt Dressing:
This vibrant yellow, citrusy dressing is a wonderful match to subtly sweet beet latkes, but that’s just the beginning. Serve it on roasted vegetables or panfried or grilled fish, or as a dipping sauce for any deep-fried snack (the acidity cuts right through the fat). It can keep for up to two weeks in the fridge, though it will probably be gone sooner.
Rinse the preserved lemon wedges and remove the seeds. Combine the preserved lemon, jalapeño (if using), lemon juice, water, honey, turmeric, salt, and oil in a food processor and puree until you have a completely smooth mixture — this may take a couple of minutes, so be patient.
Add the yogurt and pulse a few times, until the sauce is smooth and lemony yellow. If not using at once, store in an airtight container in the fridge for up to 1 week.
Variation: Keep the sauce chunky. Instead of mixing everything in a food processor, finely dice the preserved lemon and jalapeño and fold together with the rest of the ingredients.
Quick Preserved Lemons:
Combine the lemons, salt, turmeric, sugar, and 3 cups (720 ml) water in a medium saucepan and bring the water to a boil. Reduce the heat to low and simmer, stirring occasionally, for about 1 hour, until the lemons’ flesh has broken down and the rinds are very soft.
Drain thoroughly and transfer to a clean, dry jar with a lid. Pour in just enough oil to cover the lemons. Seal the jar and store in the fridge for up to 1 month. Use a clean, dry spoon or fork (never your fingers) to remove the lemons from the jar as needed. Give them a quick rinse and remove any seeds before using.