FOR THE UMAMI POWDER:
¾ ounce dried porcini mushrooms, roughly chopped
¾ cup whole raw cashews
3 tablespoons nutritional yeast
2 tablespoons raw pine nuts
1 teaspoon fine sea salt
FOR THE SAUCE:
Kosher salt and freshly ground pepper
1 medium head broccoli, cut into florets, thick stem reserved for another use
8 ounces dried pasta, such as spaghetti
½ cup loosely packed roughly chopped fresh dill, plus more for garnish
1 large garlic clove, minced
⅓ cup umami powder
½ cup extra-virgin olive oil
Fresh lemon juice, as needed
Bring a large pot of water to a boil over high heat.
Prepare the umami powder: Grind the porcini in a spice grinder until pulverized, then transfer to a food processor. Add the remaining ingredients to the food processor and pulse until the mixture is broken down into a fine meal. Transfer to a jar or lidded container. (Makes about 1 1/4 cups.)
Prepare the pasta: Season the boiling water with salt, then add the broccoli and cook until tender, 2 to 3 minutes. Use a slotted spoon to remove the broccoli, then rinse with cold water and gently pat dry with a clean kitchen towel. Add the pasta to the boiling water and cook until tender.
While the pasta cooks, prepare the sauce: In the same food processor (no need to wash it out), combine the cooked broccoli, dill, garlic and 1/3 cup umami powder; process until finely chopped. With the machine running, slowly pour in the oil. Scrape down the sides of the food processor with a spatula, and blend again, then season to taste with salt, pepper and lemon juice.
Reserve 1/2 cup pasta cooking water and drain the cooked pasta. Return the pasta to the pot, and toss with broccoli sauce, thinning with a splash of the reserved pasta water if needed to help coat the pasta. Season to taste with salt and pepper. Garnish with a sprinkle of umami powder and fresh dill.