Melt 1 tablespoon buttery spread in a skillet over medium-high heat. Add chicken and brown, cooking and stirring. Season with Montreal steak seasoning. Cook until chicken is no longer pink inside, about 5 minutes. Transfer cooked chicken to a bowl.
Melt remaining tablespoon buttery spread in the skillet. Add sliced mushrooms and garlic; cook and stir until lightly brown, about 2 minutes. Stir in water, lemon juice, and the Knorr(R) Rice Sides(TM) - Herb & Butter.
Bring to a boil over high heat; stir and reduce heat to low. Cover and simmer until rice is tender, 7 minutes. Remove from heat. Stir in cooked chicken, lemon zest, and avocado.