Place 1 lb lean ground beef in a deep stove-top pan.
Add enough water to the pan to just cover the meat.
Break the meat apart with a wooden spoon if it clumps, then stir to separate into small crumbles.
Slowly bring the pan to a boil over medium-high heat, stirring frequently to keep the meat separated.
Lower the heat, cover, and simmer until the meat is browned and cooked through, about 10–15 minutes.
Drain the cooked meat well in a colander.
Return the drained meat to the pan and stir in 1 ounce taco seasoning, if using, until evenly combined.