Heat the vegetable oil in a large skillet or Dutch oven over medium heat. Add the rice and stir continuously for 4-5 minutes until it turns slightly golden. This crucial toasting step develops a nutty flavor and helps each grain maintain its structure.
Add the diced onion to the toasted rice and sauté for 2-3 minutes until translucent. Add minced garlic and cook for another 30 seconds until fragrant.
Stir in the diced tomatoes with their juice, tomato paste, chili powder, cumin, salt, and pepper. If using, add the minced jalapeño now. Mix thoroughly to ensure even distribution of the seasonings throughout the rice.
Pour in the chicken broth and bring the mixture to a boil. Once boiling, reduce the heat to low, cover tightly with a lid, and simmer for 15-20 minutes. Resist the urge to peek or stir!
Remove from heat and let the rice rest, covered, for 5 minutes. This resting period allows moisture to distribute evenly throughout the rice. Then, fluff gently with a fork, incorporate the fresh cilantro, and serve with lime wedges for brightness.