Cut the sausage into 1/2-inch thick coins and sauté in a large, lightly oiled skillet over medium-high heat until golden brown, 2-3 minutes per side. Remove to plate.
Meanwhile, cook pasta according to package directions, drain and toss with about 2 tablespoons olive oil. You don’t need to measure; a light drizzle is fine.
Drizzle another tablespoon or so of oil into your skillet and sauté the onions over medium-high heat for 2 minutes or until starting to brown. Add the peppers and sauté another 3 minutes or until cooked but still crisp.
Add drained pasta and cooked sausage and toss. Then add feta, spinach, oregano, salt and pepper to taste and optional squeeze of lemon; toss again to incorporate.
Cook another 2 minutes or until heated through. Drizzle with another tablespoon or so of olive oil, if desired, and enjoy!