Preheat the oven to 350 degrees Fahrenheit. Mix the tuna, 1/4 cup of the olive oil, onions, salt, pepper, fresh thyme, and Dijon mustard together in a large bowl. Cover and refrigerate for 1 hour. Meanwhile, cut the top 1/4 off the garlic clove, place it on a piece of tin foil, drizzle it with olive oil, wrap it in the foil, place it on a baking sheet and roast it in the oven for 1 hour. Then remove it from the oven and allow to cool before squeezing the garlic pulp out of the clove into a small bowl. Mix the garlic with the mayonnaise, then cover and refrigerate it until use.

Cut the bread into thirds. Scoop the soft bread out of the centers of the bread pieces and then cut them in half horizontally, then lay them down insides facing up. Spread the roasted garlic mayonnaise onto the insides of the sandwiches. Spread the desires amount of the tuna on the bottom half, then layer a lettuce leaf, a few anchovy slices, several hard boiled egg slices, and two tomato slices. Place the top half of the sandwich over the fillings, encompassing them in a bread dome. Serve immediately.