2 qts or so broth, or water and fat from cooking meat
1 head cauliflower or 2 cups summer squash or other non strong tasting veggie
Fat, skin, marrow, or small meat left overs
Up to 2 tbs gelatin
1-2 tbs salt
Pepper, garlic, or other spices to taste
Bring everything to a boil and simmer for 10-20 min. Blend with immersion blender and reduce until desired consistency. It will thicken as it cools but when you warm it it will become liquid again.
I use a lot of our left overs for this. If I boil some meatballs I will make gravy from that water. If I have left over fat from cooking I will throw it in the gravy. The possibilities are endless.