Cook the potatoes, carrots, and egg: In a large pot, combine the potatoes and carrots and add water to cover. Bring to a boil over high heat, then reduce the heat to medium-high and simmer for 10 minutes. Add the egg and simmer until the potatoes are fork tender, 10 minutes more.
Marinate the tomatoes: While the potatoes are cooking, in a small bowl, stir together the diced tomatoes, vinegar, oil, and salt and black pepper to taste. Refrigerate until ready to use.
Drain and prep the potatoes, carrots, and egg: When the potatoes are tender, drain them in a colander along with carrots and the now-hard-boiled egg. Rinse with cold water to stop the cooking, then let cool. When the potatoes are cool enough to handle, remove their skins, then dice them, along with the carrots. Peel the egg, then dice it as well.
Assemble the salad and chill: In a large serving bowl, combine the potatoes, carrots, egg, tuna, peas, and red pepper. Add the mayonnaise and stir until well coated. Add salt and black pepper to taste. Refrigerate for at least 30 minutes and up to 1 day.
Serve: When ready to serve, top with the reserved marinated tomatoes. Store leftovers in an airtight container for up to 4 days. Love the recipe? Leave us stars and a comment below!
