Mix. In a large bowl, combine avocado, cauliflower, tomatoes, cucumber, onion, serrano chile, garlic, cilantro, lime juice, olive oil, salt, and cumin seeds. Stir gently to combine you don't want to break up or mash the avocado.
Marinate. Cover and refrigerate at least 30 minutes to let marinate.
Serve. Stir once more and taste. Add more salt or lime juice if needed. Serve on tostadas or with pita chips.
