Bring quinoa, broth, and cumin to a boil. Cover, lower heat, and cook for 15 minutes, or until the liquid is evaporated. Remove from heat and let sit briefly before dumping into a big bowl.
To quinoa, add the garbanzos, currants, chopped spinach, feta, olive oil, and salt and pepper to taste. The currants will plump up a little with the heat of the quinoa — this is money.
Prepare the peppers for stuffing. Lop off the stemmy top and run a knife around the inside to remove the ribs and seeds. If the peppers can’t stand on their own, carefully level the bottom, being sure not to poke a hole through to the cavernous inside. Stuff peppers with the quinoa mix and then drizzle the tops with olive oil (this well help it get a little golden brown crust on the top most layer).
Stick peppers upright in a baking dish (8- by 8-inch works well for this) and pour about 3/4 inch of water into the base around the peppers. Bake for about 1 hour (if things get too brown too fast, cover with foil and continue baking).
While peppers are baking, throw all sauce ingredients into a food processor or blender and blend until smooth.
The cooked stuffed peppers are totally attractive and you will be sad to demolish them, but demolish them you must if you are going to make the best use of this crazy addictive creamy pesto-ish magic. I like to grab a big ol’ knife and slice the pepper in half longways, from top to bottom, leaving the one pepper in two boat-shaped pieces, each filled with filling. Spoon sauce all over those things, and gobble.