Bring a pot of salted water to a boil. Prepare an ice water bath. Cook the lobsters until done, about 4 minutes, and then shock them in the ice water bath. Remove the lobster meat from the shell and roughly chop. Reserve on ice until needed.
Combine the garlic, oil, chiles, 3 teaspoons salt and 3 teaspoons pepper in a small pot and cook over medium-high heat, stirring, until the garlic is golden brown. Squeeze in the lemon juice and remove the pot from the heat. Stir well and keep warm until needed.
Cut the sourdough into 1/2-inch-thick slices, and then cut into 3 1/2-inch-long by 1 1/2-inch-wide rectangles. Melt the butter in a saucepan and add the bread. Toast the bread until golden brown on both sides. Transfer the bread into a bowl and top with the chopped lobster. Drizzle with the garlic-chile oil, sprinkle with salt and top with chopped parsley and fresh lemon juice.
Serve immediately while the croutons are still warm.