Rinse the tomatoes, poblano peppers and place all on an oven safe tray. Cook under broiler for 15 minutes or until charred.
While they are being roasted, also roast the garlic on a pan for about 5 minutes.
Take tomatoes and poblano peppers out of oven.
Place poblano peppers in a plastic container to "sweat" peppers (it makes for easier peeling).
Peel skin of both tomatoes and peppers (you can run poblano peppers under running water to peel skin and remove seeds easier with fingers).Remove stems from peppers as well.
Take half of the tomatoes and chop. Place the other half of tomatoes in a blender with garlic. Blend until smooth.
Chop poblano peppers.
Cut cucumber lengthwise and scoop seeds out with a spoon.
Do the same to the serrano peppers. Only use one pepper if you don't want the sauce too spicy and finely chop.
Chop onion, avocado and cilantro.
Mix all the chopped vegetables in with the sauce.
Add the juice of one lime, salt and pepper to taste. Done.
Serve with tortilla chips or as desired. Can also chill for a couple of hours to infuse flavors well.Note: If it's to saucy for you just remove some of the sauce until desired consistency.