Put the chicken breasts in a pot along with 1/2 an onion, 2 garlic cloves, 2 bay leaves and the 3 tsp of chicken bouillon. Cover with water and bring to a boil over high heat. Then reduce heat to low and cover. Cook for 25 minutes.

Once the chicken is done transfer it to a bowl to cool before shredding.

Roughly chop the tomatoes and measure out the chipotle peppers in adobo you'll be using.

Add the tomatoes and peppers to the blender along with 1/2 of water. Blend until smooth. Set the sauce aside.

Slice the remaining onion into thin rings then roughly chop them. Next, mince three garlic cloves.

Once the chicken has cooled shred it.

Heat up the olive oil in a large skillet over medium heat. One hot add the sliced onion and cook for a few minutes until translucent. Season with salt and pepper. Then add the minced garlic and cook for another minute.

Add the blended sauce to the skillet. Taste for salt. Season with more salt or chicken bouillon. Cook for about 5 minutes stirring ocassionally.

Add the shredded chicken to the skillet and stir until completely covered in the sauce. Cover the pot and let it simmer for just a few minutes. Remove from heat.

Spread sour cream on the tostadas. Then top with the chicken tinga and shredded lettuce.

Serve and enjoy!