While the potatoes cook (next step), prepare all your ingredients so assembly goes smoothly. Thinly slice the scallions, mince the garlic clove, finely chop the fresh oregano and dill, crumble the feta cheese, and slice the Kalamata olives. Having everything ready before you dress the warm potatoes is crucial—the warm potatoes will absorb the dressing better when you can work quickly.
Fill a large pot with water and bring to a boil. Add 1 1/2 tsp salt, then add the whole Yukon Gold potatoes (no need to peel or cut them yet). Boil for 10-12 minutes until a knife slides through the largest potato with just a little resistance—they should be tender but still hold their shape. Don't overcook or they'll fall apart when you cut them.
In a large bowl, combine the sliced scallions, minced garlic, fresh lemon juice, extra virgin olive oil, kosher salt, and freshly ground black pepper. Whisk together until well combined. This dressing will be ready to receive the warm potatoes, which will absorb the flavors beautifully while they're still hot.
Drain the cooked potatoes in a colander and give them just a 10-second rinse with cool water—this stops them from cooking further but keeps them warm enough to absorb the dressing. Once drained, cut each potato into bite-sized cubes (roughly 3/4-inch pieces). I like to leave a little skin on for texture and earthiness, but you can peel them if you prefer.
Add the warm cubed potatoes directly to the dressing bowl from Step 3 and toss gently to coat. While the potatoes are still warm, they'll soak up all the lemon and olive oil flavors. Now fold in the fresh oregano, dried oregano, and fresh dill. Add the crumbled feta and sliced Kalamata olives, and toss gently one more time, being careful not to break up the feta too much.
Let the salad rest at room temperature for about 10 minutes before serving. This allows the flavors to meld together and the potatoes to fully absorb the dressing. Taste and adjust seasoning with extra salt, pepper, or lemon juice if needed. Serve at room temperature for the best flavor.