In a large pot, bring salted water to a rolling boil. Add rigatoni and cook until al dente, about 10-12 minutes. Reserve 1 cup of pasta water before draining.

Heat a large skillet over high heat and add a splash of oil. Sear ribeye steak strips for about 3-4 minutes until browned. Remove and let rest.

In the same skillet, reduce the heat to medium, melt unsalted butter, and sauté minced garlic until fragrant, about 1-2 minutes. Add Dijon mustard, smoked paprika, lemon juice, and chili flakes.

Add the cooked rigatoni and sliced steak back into the skillet. Toss gently, using reserved pasta water to adjust sauce consistency if necessary.

Transfer to a serving dish and garnish with chopped fresh parsley. Serve warm.