Heat a large pot with oil over medium-high heat. Add diced onion and garlic, and sauté together for about 3 to 4 minutes until they become slightly tender. Tip: Stir occasionally to prevent burning.

Add the black beans, Rotel (including the liquid), and taco seasoning. Mix everything well to combine. Tip: Breaking the spaghetti in half makes it easier to fit into the pot.

Incorporate the dry spaghetti and pour in 3 ½ cups of water. Cover the pot and let it cook for 10 minutes. Tip: Check occasionally to ensure it’s not boiling over.

After 10 minutes, remove the cover and stir well, ensuring nothing is sticking to the bottom. Continue to cook uncovered for another 5 to 8 minutes, stirring occasionally until the spaghetti reaches your desired doneness and most of the liquid has cooked down. Tip: You may need to adjust the cooking time slightly based on your stove and pot size.

Once cooked, turn off the heat and stir in the cheddar cheese and sour cream until well blended. Transfer to serving dishes, garnish with sliced green onions, and serve immediately. Tip: Serve with tortilla chips for extra crunch!