In a large pot, add 1 tablespoon olive oil and heat over medium-high heat. Let the oil shimmer for a minute or two, which indicates it's hot enough for the next ingredients.
Once the oil is hot, toss in the diced onion. Sauté for about 3 to 5 minutes until the onion becomes translucent and starts to soften. This is the foundation of flavor, so stir it occasionally to prevent burning.
Add the minced garlic and continue to sauté for another minute. You want the garlic to become fragrant but not browned, as burnt garlic can taste bitter.
Next, pour in the chicken broth and the entire jar of spaghetti sauce. Stir to combine everything, letting the flavors meld together beautifully.
Add the remaining ingredients, except for the tortellini and Parmesan cheese. This includes the mixed vegetables, water, dried basil, dried oregano, and red chili flakes. Bring the mixture to a gentle simmer over low heat.
Let the soup simmer for about 20 minutes. This is the perfect time to let all the flavors mingle and deepen. Stir occasionally, and enjoy the lovely aromas filling your kitchen.
After 20 minutes, add the tortellini to the pot. Cook them for just 1 minute, stirring gently as they cook. The tortellini will soak up the broth, becoming soft and pillowy.
When the tortellini are done, turn off the heat. The residual warmth will continue to cook them just enough, ensuring they remain tender.
Now it’s time to serve! Ladle the Easy Tortellini Soup into bowls and top each serving with a generous sprinkle of Parmesan cheese. You can add extra red chili flakes if you prefer a bit more heat.
Finally, take a moment to appreciate your creation! Enjoy your hearty soup alongside some crusty bread or a fresh salad for a complete meal.