Heat a large frying pan over medium heat. Add the lean minced beef and cook for 5–7 minutes, breaking it up with a spoon, until browned and no pink remains.
Drain off any excess fat.
Turn the heat down to low and add the cubed processed cheese and the undrained tin of diced tomatoes with green chillies.
Stir occasionally for about 5–10 minutes, until the cheese has fully melted and the mixture is smooth and creamy.
Transfer the dip to a serving bowl, or keep it warm in a slow cooker set to the ‘warm’ setting. Serve immediately with tortilla chips or fresh vegetable sticks.