Whisk together the olive oil, red wine vinegar, pressed garlic, Dijon mustard, oregano, thyme, salt, pepper, and red pepper flakes in a small bowl or jar until well combined. The dressing can be made while the pasta cooks, so prepare it first to allow the flavors to meld. I like to let the dressing sit for a few minutes before using it—this helps the herbs fully infuse into the oil and vinegar.

Bring a large pot of salted water to a boil and cook the pasta according to package directions until al dente (firm to the bite, not soft). Drain the pasta and rinse it thoroughly with cold water to stop the cooking and remove excess starch. This keeps the pasta from becoming mushy and helps it absorb the dressing better.

While the pasta cooks, prepare all the vegetables: slice the grape tomatoes lengthwise into halves, slice the cucumbers into 1/4-inch quarter-moons, finely dice the red onions, roughly chop the spinach into 1/2-inch strips, and pit and halve both the green and black olives if they're whole. In a large mixing bowl, combine the cooled pasta from Step 2 with all the prepared vegetables and olives.

Pour the dressing from Step 1 over the pasta and vegetable mixture and toss thoroughly to coat everything evenly. Add the feta crumbles and a pinch of salt and pepper to taste, then gently toss again to distribute the cheese throughout. I prefer to add the feta at the end rather than mixing it in earlier—this helps the cheese stay in larger, more flavorful pieces instead of breaking down into the dressing.

Transfer the pasta salad to a serving bowl or platter and refrigerate for at least 30 minutes before serving (or serve immediately if you prefer it warm). The cold temperature helps the flavors meld together and creates a refreshing dish.