Heat the olive oil over medium heat in a large pan. Add the sliced rhubarb and onion, and saute over medium heat for 6-7 minutes, until the vegetables become tender. Add in the garlic, ginger, and crushed pepper flakes, and saute for an additional 4-5 minutes. Add the honey, soy sauce, and vegetable broth, and simmer for 15 mintes.
Add all the sauce ingredients into a high speed blender, and blend on high for a few minutes until the sauce has a thick consistency.
Serve over your favorite protein and rice/grain.
Notes
Additions and SubstitutionsIf you don't want to use honey, you can use a natural sweetener like maple syrup or agave nectar. Or use brown sugar or coconut sugar instead.For a spicier sauce, add more chili flakes, cayenne pepper, or a few drops of your favorite hot sauce.