Start a pot of boiling salted water (using ½ tablespoon kosher salt). Add the pasta and cook until al dente; add 1 1/2 cup peas to the boiling water in the last 1 minute. Drain the pasta and peas, and rinse under cold water briefly to cool.
While the pasta cooks, in a bowl whisk together 2 tablespoons olive oil, 2 tablespoons white wine vinegar, ¼ teaspoon kosher salt, and 1/4 teaspoon black pepper. Smash 1 garlic clove and add it to the bowl to marinade while the pasta cooks.
When the pasta is done, remove the garlic clove from the dressing. Pour the dressing over the drained pasta and add ⅓ cup feta cheese crumbles and 1/3 cup chopped fresh dill. Top with additional kosher salt and fresh ground pepper to taste.