Cook the pasta according to package directions, drain when the pasta is al dente. Let it cool for a few minutes.
While the pasta cooks, prep everything else, chop all your veggies and set them aside.
Then make the dressing, whisk together the olive oil, tahini, lemon juice, Dijon, agave, chilies, salt and pepper until smooth. Set aside.
Toss the cooked lentils in the olive oil and then the Za'atar, and a pinch of salt and pepper. Taste and adjust seasonings, set aside.
When the pasta is done, and had cooled down, add the pasta to a large mixing bowl, then add the veggies and feta, the lentils and the dressing to the bowl with the pasta. Toss to fully combine everything. Taste and adjust seasonings.
Serve warm immediately, or chill in the fridge and serve chilled later.