Cook macaroni according to package instructions; drain and set aside.
In a saucepan, melt butter over medium heat, stir in flour to make a roux.
Gradually add milk, whisking until smooth.
Stir in cheese until melted and creamy.
Combine with cooked macaroni and season with salt and pepper.
2. Prepare the Potato Salad
Boil potatoes until tender, then drain and let cool slightly.
In a bowl, mix mayonnaise, Dijon mustard, celery, and red onion.
Add potatoes and toss gently to coat. Season with salt and pepper.
3. Sauté the Bell Peppers
Heat olive oil in a skillet over medium heat.
Add sliced bell peppers and sauté for 5–7 minutes until tender but still slightly crisp.
Season with salt and pepper.
4. Cook the Beef Strips
Season beef strips with garlic powder, salt, and pepper.
Heat olive oil in a skillet over high heat.
Sear beef strips 2–3 minutes per side until cooked to your desired doneness.
5. Assemble the Plate
Serve beef strips alongside creamy mac and cheese, a portion of potato salad, and sautéed bell peppers.
Garnish with fresh parsley if desired.
