Place bacon in a large skillet and cook over medium-high heat, turning occasionally, until evenly browned, about 8 minutes. Drain bacon slices on paper towels; chop when cool enough to handle.
Melt butter in a saucepan over medium heat; whisk in flour. Slowly add evaporated milk, whisking until smooth. Cook until thickened slightly, about 2 minutes; remove from heat.
Add oil to a large pot or Dutch oven; cook onions over medium heat until nearly translucent. Add ground beef, and cook and stir, breaking up chunks with a spatula as it cooks, 5 to 7 minutes. Drain any excess fat.
Add bacon, diced tomatoes with green chiles, beans, and corn. Pour in beef broth and add the diced potatoes. Stir to combine. Add garlic granules, and cumin. Season with salt and pepper.
Bring soup to a boil, then reduce heat to low. Cover; simmer until potatoes are tender; 20 to 30 minutes. Pour evaporated milk mixture into soup; stir to combine. Serve immediately.
