Step 1
To make the crema, soak the raw cashews in room-temperature water to cover for at least 1 hour. Drain and reserve.
Step 2
Toast the cumin in a small, dry, heavy skillet over medium heat for about 1 minute, until fragrant. Transfer to a spice grinder, let cool, and grind finely.
Step 3
In a blender, combine the cashews, cumin, lime juice, water, and salt. Start the blender on the lowest speed and gradually increase to the highest speed. Blend for at least 1 minute, until a creamy consistency. Pour into a serving bowl and set aside.
Step 4
To make the pumpkin seeds, heat the oil in a heavy skillet over medium heat. When the oil is hot, add the pumpkin seeds and sauté for about 2 minutes, taking care that they do not burn. The seeds will begin to puff up and pop. Once they appear toasted, immediately pour them into a bowl. Toss with the cayenne and salt and set aside.
Step 5
To make the filling, heat the oil in a large, heavy skillet over medium heat. Add the onion and sauté for about 3 minutes, until softened. Add the garlic and sauté for about 1 minute more. Add the squash and sauté for 6 to 7 minutes, just until the squash begins to soften. Season with the chile powder and salt.
Step 6
Add the kale and cook, stirring, for about 1 minute, until it begins to wilt. Remove from the heat, taste, and adjust the seasoning with salt if needed.
Step 7
Serve with the tortillas, crema, pumpkin seeds, onion, cilantro, and salsa. To assemble each taco, invite guests to spoon about 1/2 cup of the warm filling into a tortilla and top with some crema and pumpkin seeds. If guests want more toppings, they can finish off their tacos with onion, cilantro, and salsa.