Saute onion and garlic in a large soup pot over medium heat.
Add broccoli, cashews, water, and salt. Cover, bring to boil, then reduce heat to simmer for 10 minutes.
Pick mint leaves off of tough stems and tear cilantro in half. Add to pot, grate in ginger, and squeeze in lemon.
Puree with a hand blender until smooth and creamy. You might need to puree soup for another minute longer than you think necessary in order to obtain the thick, creamy consistency.
Stir in cherry tomatoes to warm through and serve!
Notes: When I call for a head of broccoli in my recipes, this implies the use of the whole vegetable - the florets and the stalk. The stalk is as nutritious and delicious, and it's a waste if we don't use it. Simply use a knife to slice off the dry end and to peel away the dry, woody outer layer of the stalk (if necessary) before cutting into pieces.