Put the potatoes and garlic in a pot and cover with well-salted water. Bring to a boil over medium heat and cook until the potatoes are fork-tender, about 20 minutes; drain. When they are cool enough to handle but still hot, carefully cut the potatoes in half (try not to pull off the skins) and transfer to a large bowl. Finely chop the garlic and add it to the potatoes along with 2 tablespoons each vinegar and olive oil; season with salt. (It is important to do this while the potatoes are still warm so they absorb the vinegar and oil and are seasoned all the way through.)
Meanwhile, bring another pot of well-salted water to a boil over medium heat. Set up a bowl of ice water and season it generously with salt. Add the haricots verts to the boiling water and cook until tender, 5 to 6 minutes (bite a bean to be sure they are properly cooked); drain and immediately put in the ice water to "shock" them, or stop the cooking. When they are cold, drain the haricots verts and let them dry a little. Cut them in half.
Add the haricots verts, olives, oregano, scallions and red pepper flakes to the bowl with the potatoes. Stir to combine well; taste and adjust the seasoning. Add the remaining oil and vinegar, if needed. This salad is good now, but it will be even better if you let it sit for at least 1 hour at room temperature.
Photograph by Anna Williams
Recipe courtesy Anne Burrell for Food Network Magazine.