Alton Brown and Ina Garten have easy recipes for guacamole. Both recipes recommend using Haas avocados and both have a video tutorial available. Alton Brown's recipe takes 20 minutes to prepare, while Garten's recipe only takes 10 minutes.
For Alton Brown's recipe, place the pulp from 3 avocados and the juice from 1 lime into a large bowl. Toss to coat, then drain and reserve the remaining lime juice. Use a potato masher to mix in 1/2 teaspoon of salt, 1/2 teaspoon of ground cumin and 1/2 teaspoon of cayenne. Next, fold in 1/2 diced medium onion, 1/2 seeded and minced jalapeno pepper, 2 seeded and diced Roma tomatoes, 1 tablespoon of chopped cilantro and 1 clove of minced garlic. Add 1 tablespoon of the reserved lime juice, then let the guacamole sit at room temperature for one hour before serving.
For Ina Garten's recipe, place the flesh of 4 ripe avocados into a large bowl. Immediately add 3 tablespoons of lemon, 8 dashes of hot sauce, 1/2 cup of diced red onion and 1 large minced clove of garlic. Season with a teaspoon of salt and pepper, then toss. Finely dice the avocados in the bowl with a sharp knife and then add 1 diced and seeded medium tomato. After mixing, season with more salt and pepper to taste.