Break the chocolate into small pieces and put in a bowl. Melt with a double boiler or in a microwave. If you use a double boiler, make sure the water is not too hot.
Heat the cream up (not boiling, around 60-70℃ or 140-160℉) on a stove or microwave, then add to the chocolate. Stir gently to combine. Set aside.
Pour the aquafaba into a very clean bowl, whip for about 5 min with a hand mixer until the meringue won’t fall out when you turn the bowl upside down.
Pour one-third of the meringue into the chocolate mixture, mix to combine.
Add the rest of the meringue and fold gently from bottom to top, mix gently in order to not break bubbles that make the meringue fluffy. Do not over mix.
Pour the mousse into glasses or cups, chill for at least 2 hours.
Put the mixed berries in a small pan, add the sugar and cook it for about 5 minutes. Mix occasionally. Remove it from the heat and add the lemon juice. Let it cool. You can also make it with a microwave. Toss berries and sugar in a microwave-safe bowl until well combined. Microwave for 1-2 minutes. Add the lemon juice.