Combine garlic, 5 tbsp olive oil, 5 tbsp lime juice and salt and pepper in a sealable plastic bag. Add flank steaks and refrigerate overnight.
At dinner time:
Slice zucchini lengthwise into planks. De-seed red bell pepper and cut into large sections; drizzle with remaining 2 ½ tbsp olive oil and sprinkle with salt to taste.
Heat a grill, grill pan or heavy skillet over medium-high. Remove flank steaks from marinade and add to the grill, along with vegetables. Cook steak 3 minutes per side for medium-rare, or until done to your preference. Remove steak and vegetables from heat and let sit 5 minutes.
Thinly slice flank steaks across the grain of the meat. Place mixed greens in a bowl and top with steak and vegetables. Drizzle with extra lime juice.