For the red pepper harissa coulis: Process the peppers and garlic in a high-speed blender until smooth, about 30 seconds. Add the lemon juice, olive oil, agave nectar, oregano, harissa spice and salt, and process until very smooth. Adjust the seasoning as needed. Set aside.
For the pine nut ricotta: Combine the pine nuts, lemon juice, olive oil, nutritional yeast, shallot, lemon zest, tarragon, sea salt, garlic granules and black pepper in a blender. Blend on high speed until very smooth and thick, about 30 seconds. Adjust the seasoning as needed. Set aside.
For the squash blossoms: Gently cut a 1-inch slit, lengthwise, into each blossom. (Don't cut all the way through.) Transfer the pine nut ricotta to a 1-gallon zip-lock bag. Snip off one of the corners and pipe 1 tablespoon of the ricotta into each blossom. (You can also fill the blossoms using a small spoon, a spatula, or even a chopstick.) Pinch the blossoms closed, and plate on a bed of arugula (if using). Top each blossom with 1 to 2 teaspoons of the coulis, and sprinkle with black olives and hemp seeds.