Heat olive oil in a large pot over medium heat.
Sauté onions until translucent (about 5 minutes).
Add garlic and jalapeños; cook for 2 more minutes.
Stir in rice and sauté for another minute.
Add vegetable broth, tomato paste, salt, and optional red pepper flakes; mix well.
Bring to a boil, then simmer for around 45 minutes until the rice is fully cooked.
Remove from heat, and let it sit for 5 minutes.
Fluff rice with a fork, stir in tomatoes and cilantro.
Squeeze lime juice, give a final stir, and serve.