With all due respect to the strawberries, croutons can really make a salad, especially these croutons. Instead of tossing them with oil and baking them, we start the bread and oil in a cold saucepan for the crunchiest results.
Preheat grill to medium-high. Pat steak dry with a paper towel; season both sides with 1/2 teaspoon salt and 1/4 teaspoon pepper. Set aside.
Combine 2 tablespoons oil, vinegar, orange zest, orange juice, shallot, garlic, honey, 1/8 teaspoon salt and the remaining 1/4 teaspoon pepper in a large bowl. Set aside.
Combine the remaining 1/2 cup oil and bread in a small saucepan. Cook over medium-high heat, stirring occasionally, until the edges of the bread are golden brown, 10 to 13 minutes. Use tongs to transfer the croutons to a paper-towel-lined plate as they are done, sprinkling immediately with some of the remaining 1/8 teaspoon salt.
Meanwhile, oil the grill rack. Add the steak and cook, flipping once, until an instant-read thermometer inserted in the thickest part registers 125°F for medium-rare, 6 to 8 minutes total. Transfer to a clean cutting board and let rest for 5 minutes.
Add spinach, strawberries and the croutons to the reserved dressing; toss to coat. Slice the steak and serve with the salad.