Preheat grill to medium heat.
Brush London broil with olive oil and season with steak seasoning. Place on grill. Grill 3 to 5 minutes per side, depending on thickness and preference. When done, let rest 5 minutes then slice on the bias.
In a small bowl, combine pesto and mayonnaise.
Spread mayonnaise blend on bottom half of each ciabatta. Top with tomato slices and meat. Cover with the top halves and serve.