Marinate the steak: In a large ziplock bag, combine the marinade ingredients, seal the bag, and squish to mix. Add the steak and marinate for at least 4-6 hours or overnight for maximum flavor.
Grill the steak: Preheat your grill to medium-high heat. Grill the steak to your desired doneness (about 4-5 minutes per side for medium-rare). Rest for 5-10 minutes before slicing thinly against the grain.
Char the corn: Heat your grill or gas burner to high. Dry off the boiled corn and char on each side until golden, about 2 minutes per side. Cool and remove kernels for later.
Cook the zucchini: Heat a pan over medium-high heat with a drizzle of olive oil. Add zucchini slices, sprinkle with salt and pepper, and cook until charred, about 2 minutes per side.
Create the salad base: In a large bowl, toss the spring mix, arugula, endive, tomatoes, green onions, shallot, basil, parsley, and lemon zest. Add a pinch of salt and a squeeze of fresh lemon juice if desired.
Prepare the dressing: In a mason jar, combine the balsamic vinegar, olive oil, garlic, Dijon mustard, kosher salt, and black pepper. Shake well to emulsify.
Assemble and serve: On a large platter, layer the greens and veggies. Top with sliced steak and sprinkle with Gorgonzola cheese. Serve with dressing on the side or drizzled over the top.