Preheat the grill for medium direct heat grilling (450-500 degrees F). Use paper towels to pat the flank steak as dry as possible, then transfer to a large plate or small baking sheet. Season liberally with S&P. Place the veggies on a second plate or small baking sheet. Drizzle with just enough oil to coat, season with S&P as desired, then use your hands to ensure the veggies are coated well. Set aside.
Place seasoned flank steak on the grill grates. Arrange vegetables around the steak. Close the grill lid. Grill the steak 4-5 minutes per side to preferred doneness – about 4 minutes per side yields a nice medium rare. Grill the vegetables for 2-3 minutes per side, or until nicely charred. Transfer steak & veggies to a plate or small baking sheet. Let the steak rest for at least 5 minutes before carving.
Meanwhile, as the steak & veggies grill & rest, prep the chimichurri sauce. Add all listed ingredients to a food processor. Pulse to combine. Taste and season with additional salt or ground black pepper. Set aside,
Once the steak is rested & the veggies are cooled slightly, slice the steak against the grain. Chop veggies into bite sized pieces & spritz them with lemon juice. Build your chimichurri steak bowls as desired – I like to create a base of lemon herb rice & greens, then top with charred veggies & grilled steak. Finish with a generous drizzle of chimichurri sauce & any other toppings you like.