Prepare noodles: Meanwhile, place noodles in a large bowl; pour hot water over to cover. Don’t worry if they break a little; shorter noodles (even 6″ lengths) are common for pad thai. Let it soak for 10 minutes, after which they should be pliable but too al dente to enjoy without further cooking; longer soaks will turn the noodles mushy in the pan. Drain and set noodles aside.
Prepare the sauce: Stir together fish sauce, tamarind, brown sugar, and chili powder. Taste and adjust the flavor balance until it suits you, and it will almost certainly require some adjusting because ingredient intensity varies between brands. Ideally you’re looking for something salty followed by a mild sourness, a little sweetness, and a little lick of heat. You will add more heat and acidity at the end. Set this aside.
Crisp the tofu: Heat a large frying pan or a wok over high for a full minute, then add a tablespoon or two of oil and let this heat for a full minute too, and then add tofu cubes. Reduce heat to medium-high. Cook them until browned underneath, then use a thin spatula to turn them and cook some more, until all sides are golden and crisp. Drain on paper towels, and season while hot with a little salt and chili powder, to taste.
Cook the pad thai: Add another generous glug oil to the hot pan and, once very hot, cook garlic, shallots, and radishes for a minute, until they take on a little edge of color. Add noodles and sauce and cook until noodles absorb sauce, if needs longer to soften (you can use the edge of your spatula to try to cut them to get an idea if it’s still too firm), you can add 2 tablespoons water at a time until they’re fully cooked. You can break your noodles into shorter chunks, if you desire, with your spatula. Add half your bean sprouts and garlic chives (reserving the rest for garnishes) and toss to combine.
Push to the side, add crack your egg into empty part of pan. When halfway cooked, start scrambling, then mix into noodles. Add crispy tofu back to pan now, and toss to combine. Transfer to plate.
To finish: Around the rim, leave extra garnishes in a little piles. Squeeze lime juice over before eating (it really wakes it up).
Tamarind: This is the sticky brown acidic pulp from the pod of a tree of the pea family — it provides the signature faint sourness of pad thai. It comes in paste, and concentrate; I used the latter. Paste is the most common. To use it, reconstitute 1 part of the paste in 2 parts of water, and stir until combined. Typically, people add water to tamarind concentrate as well to use it in recipes, but I’m having us add water to the pan as needed to cook the noodles instead. Some people don’t like the intensity of tamarind. Pim says that if this is you, you use less and add white vinegar. Other swaps I’ve seen suggested online: a mixture of lime juice and brown sugar; a dab of ketchup (look, I’m just reporting here!) plus lime juice or plain vinegar.
Using other proteins: Almost all pad thai, even the most common with shrimp, has some tofu in it, usually a couple of tablespoons pressed tofu that comes in small blocks, which you can find at many Asian grocery stores. Here I’m calling for firm or extra-firm, which come in water and are easier to find, and making it the star of the show. If you’d like to use shrimp here instead, I’d estimate 6 medium fresh shrimp, peeled and deveined, per serving, and you can par-cook it with the garlic, shallot, and radish in the beginning. Don’t fully cook it, it will finish with the noodles and sauce over the next few minutes. If you’d like to use chicken or pork, I’d estimate 2 ounces, chopped in rough chunks, per serving, and cook is as you would the shrimp. Want to use none of the above? An extra egg might give your pad thai all the protein you wish for. Finally, quite often, the egg is cooked along with the shrimp in the beginning but I prefer mine added closer to the end so it’s a bit more present.
Eggs: Are optional in pad thai. In Thailand, they’ll ask you when you order it whether or not you want it. Sometimes it is scrambled in, other times a paper-thin omelet is poured made and the pad thai is wrapped inside it, like a crepe. I’ll save that for Pad Thai for Intermediates.
Palm sugar: Is the standard sweetener in pad thai, not brown sugar, but on this, I defaulted to what was already in my pantry. I think coconut sugar could be a good swap too. Palm sugar often comes in semi-solid blocks; you’ll want to scrape some off and warm it in the microwave or over another heat and it will loosen. For pad thai sauce, cooks will often melt the palm sugar in a pan and add the other sauce ingredients, just to warm them until liquefied. For palm sugar, you’ll want to use a bit more for the same level of sweetness; I’d use 3 teaspoons for every 2 here, but of course you’ll adjust this to taste too. Finally, palm sugar these days can be purchased in granulated form.
Fish sauce: Is salty and a little funky, and is the magic ingredient is so many of our favorite dishes. Between brands and even countries where its manufactured, saltiness and funkiness vary a lot. Vietnamese fish sauce is usually considered sweeter/less salty than Thai. Red Boat is one of the most popular; I had MegaChef and Squid brands around — the latter is probably the strongest/saltiest I tried. I haven’t tested it out, but vegetarian fish sauce is available. Here is a brand with good reviews; it sounds like you’ll want to use more to get the same intensity.
Sweet preserved radish: This provides a unique chewy sour/salty sweet flavor throughout in slightly crunchy bits I really enjoy it here, but I do think your pad thai can still taste good without it, you just might find you need a little more of the other sweet ingredients, such as tamarind and palm or brown sugar.
Shallots: I only spotted these in a minority of the recipes I perused, but made mine with and without them, and liked them here. I felt that the cooked shallot + pad thai sauce faintly reminded me of the preserved radish flavor, too, so definitely worth including if you can’t find the radishes. If you don’t have a shallot and are using the green part of scallions instead of garlic chives, might you use the white parts as you’d use the shallot here? Oh, I like the way you think.
Bean sprouts: Are crunchy and fantastic here. If you can’t find or get them, I bet shredded white cabbage or very thin juliennes of napa cabbage might provide a similarly refreshing crunch. I’d barely cook them.