How to introduce avocado

Hi !!! So one time at around 8 month I started introducing avocado, and then by 9 months I gave my daughter probably more than she could. Because she started having red spots immediately, they dissapeared next morning, gave me and husband heart attack. So I never gave her avocado again. Untill recently. And turns out now she doesn't like it, spits it immediately. Is there any was to make her like avocado ? How do you prepare avocado for you lo? Because I love avocado and would like to give for baby too since is naturally rich product