Fry onion, garlic, and white stems of chard until barely limp. Add chopped greens and fry a bit. Either peel the yams or scrub them well with a vegetable brush, then slice them into thick slices. Add garbanzos, raisins, yams, tomatoes, salt, and pepper. Cook a couple of minutes. Make a well in the center of the mixture in the pot. Put the rice in the well and pat it down until it's wet. Cover and cook until rice is done\(emabout 25 minutes. Add Tabasco sauce to taste. I find that the flavors of the vegetables don't stand out unless you put in a lot of tabasco. But then, I've got a cast-iron tongue. You should add enough to make the stew seem spicy to you.

Precision: no need to measure.