Preheat your oven to 400°F (200°C) and line a small baking sheet with parchment paper.
Toss the chopped zucchini and red bell pepper with a half teaspoon of olive oil and a pinch of salt, then roast for 15-20 minutes until tender.
While vegetables roast, bring a small pot of water to a boil, gently lower the egg in, and cook for 6.5 minutes for a jammy yolk.
Immediately transfer the egg to an ice bath, then peel and set aside.
Season the sirloin steak with salt and pepper, then grill over medium-high heat for 3-4 minutes per side or until desired doneness is reached.
Let the steak rest for 5 minutes before slicing thinly against the grain.
In a small bowl, whisk together the remaining olive oil, lemon juice, and Dijon mustard to create the vinaigrette.
Place the arugula in a large bowl, top with the roasted vegetables and sliced beef, then add the halved egg.
Drizzle the lemon vinaigrette over the salad and enjoy immediately.