In a soup pot sauté the onions and salt with ¼ cup of water for 10 minutes until the onions are translucent. Stir often and add water as needed to prevent burning.
Add the garlic, ginger, cumin, coriander, and red pepper flakes and cook for another 30 seconds.
Add the broccoli and vegetable broth and bring to a simmer. Simmer, partially covered, for 3 minutes or until the broccoli is bright green. Next add the green peas and turn the heat off.
Carefully (but quickly) transfer the soup to a blender and add the spinach, lemon zest and juice, and tahini or cashews (if using). Blend on high until completely smooth. Taste and reseason with salt and pepper as needed. Add more broth if desired to thin the soup and blend again. Pour into bowls and enjoy!