Step 1 In a large pot of boiling, salted water, cook the pasta until al dente, 8 to 10 minutes, or according to the package instructions. Drain, very lightly oil (to keep the pasta from sticking) and set aside.
Step 2 In a medium saucepan, cook one-third cup of the cilantro (reserve the rest for garnish), garlic and jalapeno with 2 tablespoons of butter over medium heat until aromatic and the garlic is golden, 4 to 5 minutes. Stir in the broth, tequila and lime juice. Bring the mixture to a boil and cook until thickened to a paste-like consistency, 6 to 8 minutes. Remove from heat and set aside.
Step 3In a small bowl, drizzle the soy sauce over the chicken pieces and set aside to marinate for 5 minutes.
Step 4Meanwhile, in a large saute pan, heat the remaining butter over medium heat. Add the onion and red, yellow and green peppers, and cook, stirring occasionally, until the vegetables have wilted. Stir in the chicken and soy sauce, then the tequila/lime paste and cream.
Step 5Bring the mixture to a gentle boil and cook until the chicken is cooked through and the sauce is thickened, several minutes. When the sauce is done, stir in the fettuccine and remaining cilantro.
Step 6Serve the dish family-style or plate on individual serving dishes. Serve immediately.