Combine broth, agave, soy sauce, sesame oil & rice vinegar in a large and shallow glass pyrex. Cut each of the slabs in half to create 8 squares, then place the tofu into the marinade. Cover and refrigerate overnight. Flip the tofu at some point in case the tofu is not totally submerged in the marinade.

When you are ready to make the dish, place 5 TB of the marinade into a skillet over medium-low heat. Add in the ginger and saute for about a minute. Add in the pak choy and salt, and allow to soften for about 5 minutes, stirring occasionally. Add to a blender and allow to cool while you prepare your tofu.

In the same pan, add in about 3 TB of the marinade, then add in the tofu. Increase the heat to medium. Allow to saute for about 5 minutes. Check the bottom of the tofu—if it is nicely browned, flip it over, then allow to saute for an additional 5 minutes. Check it occasionally to ensure it does not burn. Transfer to tofu to a separate plate to slightly cool.

Add in 3 TB of the marinade to the pan. Place the shiitake caps into the pan, then cover. Allow to steam for 3-5 minutes. Once softened turn the heat up to nicely brown the mushrooms.

By now, your puree should be cooled enough to safely puree it. Puree until smooth, adding a little bit more of the marinade if needed. To serve, stack the tofu and shiitake, then drizzle with the pak choy puree.