Preheat the oven to 400 degrees F. Cut the tomatoes in half and using a small spoon, remove the seeds. Season with olive oil, basil, thyme, garlic, salt and pepper. Place on a parchment-lined baking sheet, seed side down and roast for 25 minutes. Remove from the oven and cool. Season the asparagus with olive oil, salt and pepper. Place on a parchment-lined baking sheet and roast until tender, about 15 minutes. Remove from the oven and cool. In a mixing bowl, combine the mayonnaise, mustard, lemon juice, and tarragon. Season with salt and pepper. Mix well. Fold in the crabmeat. Line a 12 1/2 by 4 1/2 rectangle porcelain terrine mold with plastic wrap, allowing the plastic to hang over the mold by 2 inches. Line the bottom of the mold with half of the tomatoes. Lay half of the asparagus over the tomatoes. Spoon half of the crab mixture over the asparagus, using the back of the spoon, press the crab mixture slightly into the vegetables. Repeat the above process with the remaining ingredients. Cover the terrine tightly with the plastic wrap. Place a couple of weights or 3 (1 pound) cans on top of the plastic to press the terrine. Refrigerate for at least 12 hours or up to 2 days. Remove from the refrigerator. Using an electric knife, slice the terrine into 1/2-inch slices. Remove the plastic wrap. Place 2 slices of the terrine onto each serving plate. Drizzle each slice with the extra-virgin olive oil. Season with salt and pepper. Mound some the maiche in the center of the plate. Garnish with parsley. Serve with the croutons, if desired.