I use this recipe from All recipes:

Chicken Fajita Marinade

Prep Time: 15 Minutes
Ready In: 15 Minutes
Servings: 6
"This easy to make marinade will give your chicken just the flavor you're looking for next time you're making fajitas!"
Ingredients:
1/4 cup beer
1/3 cup fresh lime juice
1 tablespoon olive oil
2 cloves garlic, minced
1 tablespoon brown sugar
1 tablespoon Worcestershire sauce
1 tablespoon chopped cilantro
1/2 teaspoon ground cumin
salt to taste
Directions:
1. To prepare the marinade, stir together beer, lime juice, olive oil, garlic, brown sugar, Worcestershire sauce, cilantro, cumin, and salt; mix well.
2. To use marinade, pour into a resealable plastic bag, add up to 1 1/2 pounds of chicken breast, and mix until chicken is well coated. Marinate for 1 to 3 hours in the refrigerator.
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For fajitas I marinate, over night or all day in a mole sauce...sort of.
I sautee a small onion in a bit of olive oil...add a couple of cloves of crushed garlic when the onions are limp, add cup of chicken broth, a rounded teaspoon of sugar and 2 rounded tablespoons of prepared mole paste.
Simmer until well mixed and onions are soft....about 10 minutes....cool and pour into plastic bag with chicken and refrigerate.
Believe me you will have flavor in the chicken.
Linda C

There used to be a mexican restaurant here that had *the* best fajitas. After he closed the restaurant he told me his secret. Eazy, peazy. Equal amounts of soy and honey. Squeeze fresh lime over just before serving.
Still haven't tried it. But I think I have everything I need except for the flour tortillas. This is going on the menu soon!

I've used soy sauce and honey on lots of things...like pork, beef, chicken and salmon....but though delicious, I never thought it had a particularly "Mexican" flavor.
Linda c

As a marinade I think lime and cumin are going to give to the best bang for your buck . Add whatever else you like spice-wise in the fajita pan when you fire it.

I use the following:

1 Tbsp chili powder
2 Tbsp ground cumin
2 Tbsp seasoned salt
2 Tbsp minced garlic
1 Tsp dried oregano
1 Tbsp oil
Juice of one lime
Hot pepper flakes to taste

I'm just guessing at the proportions - I usually just measure out stuff in the palm of my hand depending on how much chicken I have. I've also used this for beef as well, but I mostly make chicken fajitas. And I like cumin, so I always add twice the amount called for. Sometimes I use garlic powder if I have no fresh garlic on hand but the fresh is much better. The recipe also called for a little paprika, but until I found really good, fresh Hungarian paprika, I didn't bother because it usually has no taste. I also use ground chipotle in place of the flake red pepper on occasion if I'm in the mood for a smokier flavor. I've let it marinate overnight and I've done it a couple hours ahead.

Lisa

I do something similar to Linda. I make up my mole dry rub...

MOLE DRY RUB

¼ Cup Cocoa
2 Teaspoons Chipotle Powder
2 Teaspoons Ancho Powder
1 Teaspoon Ground Cumin
1 Teaspoon Powdered Garlic
1 Teaspoon Dehydrated Thyme
1 Teaspoon Cinnamon
½ Teaspoon Ground Allspice
½ Teaspoon Ground Paprika
2 Teaspoons Sea Salt
1 Teaspoon Black Pepper

Then, add olive oil to make a medium-thick paste. Add the juice of one lime. Smear it all over the pre-sliced chicken, put in a Zip-Lock & refrigerate for an hour.

/tricia

I apologize in advance. I donÂt have measurements I just usually throw this together.

Frozen limeade concentrate
Ground cumin
Ground coriander
Minced or pressed garlic
Chopped cilantro
A little chili powder

Thaw limeade and mix with other ingredients. Add chicken. I usually use a Ziploc bag for this and marinate 3 hours or so. Or you can marinate overnight but no longer, the flavor is overpowering if marinated any longer.

Well I ended up buying McCormicks Baja Citrus Marinade and grilled the chicken. It was fabulous! The marinade really penetrated the chicken.

I think it is expensive at $1.69 though for the package.