Place 1 cup water and 1 TBSP butter in a small pot. Bring to a boil, then add rice and stir once. Reduce heat to low, bring to a gentle simmer, and cover. Cook until tender, about 15 minutes. Remove pot from heat and keep covered.

Wash and dry all produce. Halve, peel, and thinly slice onion; mince a few slices until you have 2 TBSP minced onion. Halve, core, and seed bell pepper, then thinly slice. Core, seed, and finely dice tomato. Finely chop cilantro. Halve lime; cut one half into wedges.

Heat a large drizzle of oil in a large pan over medium-high heat. Add onion and bell pepper. Cook, tossing, until just softened, 3-4 minutes.

Add another large drizzle of oil to pan with veggies. Tear chicken into smaller pieces and toss into pan. Season with salt, pepper, and fajita spice. Cook, tossing, until chicken is warmed through, 2-3 minutes. Stir in stock concentrate and 1/2 cup water. Bring to a boil, then reduce heat to low and stir in 1 TBSP butter. Let simmer until saucy, 1-2 minutes.

While chicken simmers, place tomato, minced onion, and half the cilantro into a small bowl. Squeeze in juice from lime half. Season with salt and pepper, then toss to combine

Fluff rice with a fork and season with salt and pepper; divide between plates. Spoon chicken, veggies, and their sauce over rice. Top with salsa and cheese. Dollop with sour cream. Serve with lime wedges on the side for squeezing over.