Slice the avocado and refrigerate it in a small covered container.
Prepare the blue cheese dressing, and refrigerate until ready to assemble.
Prepare the Marinade
Put the dry mustard in a shallow bowl. Add the vinegar and mix with a whisk. Holding the whisk in one hand, gradually add the olive oil, whisking the whole time. The mixture will thicken slightly.
Make the Grilled Onions
Combine the tomato and cucumber in a bowl.
Heat an iron skillet, and add the olive oil. Sauté the onion until it is translucent. Remove the onions and put them in the bowl with the tomatoes. Pour the marinade over them, and chill until ready to assemble.
Make the Grilled Steak
Grill the steak slices in the same pan, about two minutes on each side. Just before they are done, add the Worcestershire sauce, flip to coat both sides. Remove from the pan and let the steak rest about 5 minutes before slicing.
Slice the steaks in 1/2 inch strips against the grain. Refrigerate until ready to assemble.
Make the Croutons
Meanwhile, add the butter to the same pan, and let it melt. Then add the garlic and sauté until the garlic is soft about two minutes. Add the cubed bread, and cook, stirring frequently until the bread is crisp and coated. Remove from the pan, and cover loosely until ready to assemble.
When you are ready to assemble, have ready a large shallow serving bowl, a pasta bowl makes a good choice.
Take the large outer leaves of the lettuce and line the bowl with those, fanning out the leaves nicely.
Tear the remaining lettuce into smaller pieces into the bowl.
Put the croûtons on the outside.
Fill with the marinated vegetables.
Put the slices of steak on top of the vegetables in a line, allowing the vegetables to show under.
Top with the avocado slices.
You can refrigerate until ready to serve.
Serve with the blue cheese dressing, separately.
This is a great salad for the grill. All the vegetables, and of course, the steak, can go on the barbecue. Keep your kitchen cool in the summer!You can make this completely vegan by not including the steak, and using a vegan dressing.