Make the flavor paste: Add the onions, garlic, ginger, scallions, lemongrass paste, coriander, Thai chilis, and oil to a food processor. Blend until you get a paste. You may need to scrape the sides of the bowl to ensure all the herbs and spices are fully chopped. Transfer the paste to a large pot.
Cook the broth: Heat the pot over medium heat and cook the flavor paste for about 1 to 2 minutes, stirring frequently to keep it from burning. Add the curry powder, vegetable stock, honey, and salt, and bring the broth to boil. Once it boils, add the coconut milk and stir.
Cook the noodles: Bring a small pot of water to boil and cook the rice noodles according to package instructions. I used wide noodles, so they took a little longer to cook (about 8 to 9 minutes). If you are using rice noodles, make sure to stir them a few times to keep them from sticking to each other. Once cooked, drain and rinse the noodles under cold water.
Add the Tofu and Vegetables: Add the tofu puffs, carrots, and bean sprouts, and cook them for about 2 minutes. I like leaving some uncooked bean sprouts and carrots on the side for serving because I like the crunch of those vegetables raw.
Serve: Add the lime juice and taste the broth to see if it is to your liking. Adjust the seasonings to your taste. Divide the noodles into bowls and ladle broth, tofu, and vegetables over the noodles. Serve the noodles with cilantro, sliced scallions, chopped peanuts, and lao gan ma spicy chili crisp, if desired.