Add 2 tablespoons of oil to a medium skillet; add the onion, garlic and jalapeno chiles and saute just until the vegetables soften a little. Set the mixture aside and allow it to cool.
Place the avocados, lemon juice, cilantro and broth in a large bowl (preferably with a pouring spout) and stir to combine.
Work in batches and pour the mixture in a blender and blend until it is very smooth. Pour the blended soup in another bowl, repeat for all the avocado mixture. The soup will be thick. If you prefer a thinner soup you can add a little water. Season the soup with salt and pepper, then taste and adjust the seasoning as needed.
Chill the soup for at least an hour or two and it gets even better the next day. Serve chilled with any of these optional condiments. We served ours with a little sour cream and some fresh cilantro leaves.
Sour cream (shown)
Chilled cooked shrimp
Thin strips of fried tortillas