Adjust rack to middle position and preheat oven to 425 degrees. Wash and dry all produce. Halve poblanos lengthwise; remove and discard stems and seeds. Drizzle each half with oil; season with salt and pepper. Place on a baking sheet and roast on middle rack until softened, 15 minutes.

While poblanos roast, bring 1¼ cups salted water to a boil in a small pot. Stir in rice, then cover and reduce heat to low. Cook until rice is tender, 15 minutes. Meanwhile, halve, peel, and dice onion. Dice tomato. Zest and quarter lime. Mince chili. In a small bowl, combine sour cream, 1 TBSP water, and lime zest to taste. Season with salt and pepper.

Heat a large drizzle of olive oil in a large, preferably ovenproof, pan over medium-high heat. Add onion and cook, stirring occasionally, until slightly softened, 3-4 minutes. Stir in stock concentrate, Southwest Spice, half the tomato, 2 TBSP water, salt, and pepper. Cook, stirring, until softened, 2-3 minutes. Turn off heat.

Stir cooked rice into pan until thoroughly combined. Return pan to medium-high heat. Stir in 1 TBSP butter until melted. Turn off heat. Season with salt and pepper.

Once poblanos are done roasting, stuff each half with as much filling as will fit. Nestle into pan with remaining filling. Sprinkle poblano halves with Monterey Jack. Bake until cheese is melted and slightly crisp, 7-8 minutes.