Place the eggs in a pot and cover them with cold water. Bring the eggs to a boil on the stovetop. Once the water starts to boil, set a timer for 8 minutes. Remove from the heat, drain the water, and run the eggs under cold water, then let sit for 5 minutes to cool. Then peel and chop.
Season both sides of the sirloin well with steak seasoning. Set aside.
Preheat a skillet or non-stick pan over medium heat. Once hot, cook the steak on both sides to your desired temperature using a thermometer (see below). (For thicker steak or for more well done, finish cooking the steak in a 350°F (176°C) oven so the outside doesn’t burn before the inside is done to your liking.)
Once cooked, set aside to rest for 3-5 minutes before dicing into bite sized pieces.
Toast the bread then spread it with butter and garlic.
For the dressing: whisk together all of the ingredients in a bowl until fully combined. Season with salt and pepper. Set aside.
Lay down the lettuce and top with sliced steak, hard-boiled eggs, avocado, cucumber, tomato, onion, and blue cheese.
Dress the salad, serve with bread, and sparkling water.