Put the yogurt in a medium bowl, add the basil and parsley, and stir to combine.
Set aside.
Mince the garlic.
In a medium bowl, whisk together the garlic, vinegar, mustard powder, salt, and black pepper.
While whisking, slowly drizzle in the olive oil until emulsified.
Cut the tomatoes and cucumbers into ¼-inch dice; you should have about 1 cup of each.
Shred the romaine.
Cut the yellow bell pepper in half, discard the seeds, and cut into ¼-inch dice.
Peel and grate the carrots.
To assemble the parfaits, layer the bottom of each of four parfait glasses with ¼ cup diced tomatoes, followed by ¼ cup diced cucumbers and ½ cup shredded lettuce.
Gently press down with the back of a spoon to pack the ingredients.
Top with 2 tablespoons of the yogurt mixture, ¼ cup of the diced yellow pepper, and then ¼ cup of the shredded carrots.