Preheat the oven to 325°. If you plan to use convection, skip this step . Place your bread chunks on a baking sheet, spray lightly with cooking spray but enough to coat and season with salt and pepper. Once the oven is preheated, place the baking sheet with the bread in the oven and toast for 7-9 minutes until turning golden but a tiny bit soft in the centers. It's better to overdo this step than to not toast long enough. If using convection, don't preheat the oven. Just turn it on to 325° when you put the baking sheet in.
While the oven is preheating, place a cast-iron grill pan on the stove over medium-high heat. Leave it to preheat while you prepare the vinaigrette. In a large serving bowl whisk together the vinegar, juice of 1 lime and 2 tbsp of olive oil until emulsified. Season with salt and pepper and set aside. Chop the tomato and cucumber and add to the serving bowl. Chop the arugula and herbs and set aside.
Your grill pan is now nice and hot. Spray your corn cobs with cooking spray and place in the hot pan. Turn each cob 1/4 turn every minute or so until you have nice searing around the entire cob. Using tongs in one hand, remove from pan and hold upright in your serving dish. Use a sharp knife in your other hand to cut the kernels off the cob and let them fall into the serving dish.
Turn off the heat for the grill pan. Place your pre-prepared carne asada in the pan and cook for 2 minutes on each side while the pan is still nice and hot. This will reheat the meat just enough to make it juice but without losing that beautiful medium-rare color. Remove from the pan, cut into strips and then into bite-sized chunks. Add to the serving bowl.
Remove bread from the oven and add to the serving bowl. Using a large fork and spoon, toss well to ensure everything gets coated with the dressing. Add the arugula and fresh herbs and toss lightly again to combine. Split between 2 serving bowls. Sprinkle each serving with half of the Cotija cheese and half of the pepitas. Serve immediately.