Copycat Taco Bell Nacho Fries

Name: Copycat Taco Bell Nacho Fries
Ingredients: 1 (28- to 32-ounce) bag frozen seasoned french fries, such as Ore-Ida Zesty straight fries; 1 medium Roma or plum tomato; 2 medium scallions; 4 ounces sharp cheddar cheese, preferably yellow, shredded (about 1 cup); 4 ounces Velveeta processed cheese; 8 ounces lean ground beef or plant-based ground beef; 1/2 teaspoon kosher salt, plus more as needed; 1 cup whole or 2% milk; 1 tablespoon store-bought or homemade taco seasoning; 1/4 cup water; 1/3 cup sour cream; Hot sauce, for serving (optional)