Pack the mustard greens into the slow cooker and pour in
In a large skillet or sauté pan, heat
Continue to cook the remaining onion mixture in the skillet over medium-low heat until very deeply browned and soft, adding a splash of water, if needed, to keep the onion from sticking, 10 to 15 minutes. Add the mustard seeds and set aside in the skillet until evening.
Reheat the onion and mustard seed mixture.
Using an immersion blender, puree the ingredients in the cooker until very smooth, adding the cream cheese and blending to incorporate it. Season with salt, if needed, and cover to keep warm.
Cut the tofu into slabs or small squares ¼ to ½ inch (6 to 12 mm) thick and pat dry with a paper towel. In a large skillet or sauté pan (or using a large griddle), heat the remaining