For the beef: Smash the garlic cloves with the side of your knife, and then remove the skins and roughly chop. Pour the olive oil over the steak, and then sprinkle with the garlic and marinate for 1 hour.
For the kale chips: Preheat the oven to 350 degrees F. Drizzle the olive oil onto your hands and gently rub each leaf lightly with the oil. Lay the leaves flat on a baking sheet and bake for 40 minutes. Remove from the oven and let cool. Leave the oven on for the beef.
For the dressing: Meanwhile, blanch the broccolini in boiling water for 5 minutes. Pat the pearl onions dry and place in a skillet over medium-high heat. Sear the onions in the oil to brown all sides, about 2 minutes. Remove and let drain on paper towels.
For cooking and assembling the beef: Preheat a grill to high heat. Remove the meat from the marinade and sprinkle with salt and pepper. Sear the meat on all sides over a hot open fire, and then grill for about 8 minutes per side.
Transfer the meat to the oven and roast until medium rare, 8 to 10 minutes. Remove from the oven and let rest for 7 minutes. Slice the steak against the grain into 18 thin slices for 2 portions.
To serve, divide the crispy kale chips between 2 plates and lay flat in the center with the ruffled ends facing out. Mix together the hot sliced steak, arugula, tomatoes, pearl onions and broccolini florets in a large bowl. Spoon on 2 to 3 tablespoons of three-herb chimichurri sauce. Add a splash of hot pepper vinegar, if using. Season with a pinch of salt and fresh cracked pepper. Toss well and add any beef drippings back into the dressed beef. Garnish with the amaranth blossoms and bread sticks, if using, and serve over the kale chips with any remaining chimichurri on the side.