Step #1 Put oil in a 9- to 10-inch ovenproof frying pan.
Step #2 Add sage leaves & mix to coat with oil, then lift out leaves & put in a small bowl.
Step #3 Peel & thinly slice onion.
Step #4 Put onion in frying pan over medium-high heat & stir often until golden & sweet-tasting, about 10 mins.
Step #5 Meanwhile, in a bowl, whisk garbanzo flour & 1/4 tsp salt with 1 1/2 c water until smooth.
Step #6 Reduce heat under onions to medium-low.
Step #7 Push onion slices to center of pan & pour garbanzo mixture around them, then lift onions so batter can flow under them.
Step #8 Sprinkle top socca with sage leaves.
Step #9 Cook until socca feels dry when lightly touched & is browned on the bottom (lift carefully with a spatula to check), 12 to 14 mins.
Step #10 Broil 6 to 8 inches from heat until top is lightly browned, 3 to 4 mins.
Step #11 Cut into wedges & serve this with a wide spatula.
Step #12 Add salt to taste.
Step #13 Canned option: If garbanzo flour isn't available, omit it from preceding recipe.
Step #14 Instead, drain 1 can (15 1/2 oz.
Step #15 ) garbanzos, reserving 6 tbsps of the liquid.
Step #16 Whirl garbanzos, reserved liquid, & 1 tbsp all-purpose flour in a mixer until very smooth.
Step #17 Use in step Mixture will still feel moist on top when browned on bottom, & will take 3 to 4 mins longer to brown when broiled, step 4, step Nutritional analysis per appetizer serving.