Let them steam for about 5 -8 minutes, checking them every so often for two reasons: 1. Is the water still making steam? If not, your pan is too cold. Turn the heat up. OR, you burned off all your water and you need to add more if the babies aren't done yet. 2. Are they done yet? Poke them through the center with a good knife to see how tender they are.
When they seem appropriately tender (use your own judgment. Pull one out and taste it if you don't trust yourself), take the lid off and turn the heat back up to boil off any remaining water. When the water is gone, the babies will saute a little in the dregs of the oil. I like to let them brown just a wee bit because they look prettier. When they look about right, pour them out into a bowl and dress with salt, pepper, olive oil (if you want) and acid of your choice (lemon or wine vinegar).
From here, you can marinate them for a salad, or slice them for a pasta sauce, or whatever. The whole shebang, from taking them out of the fridge until dumping them out of the pan, takes about 20 minutes. I'm not doing this on a work night, but when they're on sale and it's the weekend and I happen to feel like it, well, there you go.