Preheat the oven to 400°F. Place a large pot of water over high heat and bring to a boil. Rinse and dry the yellow squash, scallions, carrots, and lime. Slice the yellow squash into thin rounds. Chop the scallions into 2 inch long pieces. Peel the carrot then continue to peel lengthwise to create “noodles” with your peeler. Halve the lime.
Rinse and dry the broccoli. Transfer to a baking sheet. Toss with 1 tbsp vegetable oil, a pinch of salt and pepper, and black sesame seeds. Roast until slightly browned in places, about 8 to 10 minutes. Once the water is boiling, add the rice noodles and turn off the heat. Sir occasionally until noodles are tender, about 8 to 10 minutes. Drain and run under cool water.
Place a large skillet over medium-high heat and add 1 tbsp vegetable oil. Once the oil is hot, add the yellow squash, scallions, and carrot. Sprinkle with salt and cook, stirring frequently, until the carrots have wilted slightly, about 2 minutes.
In a medium bowl, whisk together the juice from half the lime, cashew butter, dark soy sauce, ¼ cup hot tap water, and as much of the sambal as you’d like. Add the sauce to the skillet with the vegetables. Then add the rice noodles. Reduce heat to medium and cook until noodles are warmed through, tossing frequently, about 3 to 4 minutes.
Chop the peanuts and set aside. Rinse and dry the cilantro. Pick the leaves and tender stems, discard the tougher stems, and chop. Roughly chop the kelp noodles. Transfer to a small bowl. Add the juice from the remaining half of lime, sesame oil, hemp seeds, peanuts, chopped cilantro, and a pinch of salt. Toss kelp salad to combine.
Divide the vegetable pad thai and roasted sesame broccoli between your plates. Top with the kelp salad and serve with any remaining sambal.