In a large, wide pot fitted with a steamer basket, bring about 1/2 inch of water to a boil over medium high heat. Arrange the potatoes in an even layer in the steamer and sprinkle with 1/2 tsp. salt. Cover and steam, carefully stirring every 5 minutes or so, until the potatoes are just tender, 10 to 15 minutes total. Let cool briefly and then transfer to a large bowl.
While the potatoes are steaming, finely grate the zest from the lemon and then juice the lemon. Put the zest in a food processor and set the juice aside. Add the garlic to the food processor and pulse a few times. Add the herbs and pulse to coarsely chop. Add the olive oil, 1 tsp. salt, and 1/2 tsp. pepper and pulse until the mixture is fairly homogenous, scraping down the sides of the bowl as necessary. (Avoid overprocessing or the herbs will heat up and discolor; 10 to 12 pulses should do.) Add 3 Tbs. of the lemon juice and pulse once to mix.
Drizzle the herb mixture over the potatoes and toss gently to combine. Season to taste with more salt or lemon juice. Serve warm.
nutrition information (per serving):
Photo: Scott Phillips