Place the bread cubes onto a baking sheet. Drizzle with the olive oil and sprinkle with the salt and pepper. With clean hands, gently toss to coat all of the bread cubes. Layer in a single layer on the baking sheet. Place in the oven and bake until lightly toasted, about 4 minutes. Once baked, removed from the oven and allow to cool as you assemble the salad and the dressing.
Place the romaine hearts, tomatoes, and chopped bacon into a large bowl. Add the cooled bread cubes and gently toss together to combine well.
For the dressing:
Add the red wine vinegar, mustard, olive oil, water, salt and pepper to a mason jar with a tight-fitting lid. Shake until well-combined, about a minute. Drizzle half over the salad and toss to lightly coat.
Serve remaining dressing on the side of the salad.
Notes
Slightly adapted from Shelly Jaronsky's, Cookies and Cups Cookbook (Gallery Books, 2016)