Place the dried red chilies in a heatproof bowl and cover them with boiling water. Allow them to soak for 10 minutes, then drain and discard the soaking water.
Prepare the laksa paste by adding the soaked chilies, garlic cloves, peeled ginger, lime zest, lime juice, raw cashews, fresh chili, sambal chili paste, oil, and chopped shallots to a food processor.
Process the mixture until a smooth paste forms. Scrape down the sides of the food processor as needed to ensure the paste is evenly blended.
Transfer the laksa paste to a bowl. Use half of the paste for the soup. Store any remaining paste in an airtight container in the refrigerator for up to 1 week.
Bring a large pot of water to a rolling boil. Cook the rice noodles according to the package directions until tender.
Drain the cooked rice noodles and set them aside until ready to serve.
Heat a skillet or soup pot over medium heat. Add half of the prepared laksa paste.
Sauté the laksa paste for 1 minute to develop its flavor and reduce the raw taste of the shallots, garlic, and spices.
Add the thinly sliced zucchini to the pan. If using additional vegetables such as mushrooms or bell peppers, add them at this stage.
Cook the vegetables until crisp-tender. They should be softened but still retain some texture.
Pour in the vegetable stock and coconut milk. Stir until the laksa paste is fully incorporated into the liquid.
Add 1 tsp sugar, 1 tbsp lime juice, and a generous pinch of salt. Stir to combine.
Bring the soup to a boil, then reduce the heat and simmer for 1 to 2 minutes, or until the broth begins to thicken slightly.
Remove the soup from the heat. Taste the broth and adjust with additional salt, sugar, or lime juice as needed.
Divide the cooked rice noodles evenly among four serving bowls.
Ladle the hot laksa soup over the noodles, dividing the broth and vegetables evenly.
Top each bowl with thinly sliced tofu, cucumber slices, chopped cilantro, and additional chilies if desired.
Serve immediately with lime wedges on the side.