Wash all the fruits under cold water. Slice strawberries and apple, halve grapes, and drain mandarin oranges. Combine all fruits in a bowl and add lemon juice.

In a separate bowl, whisk together softened mascarpone cheese and plain yogurt until smooth. Add honey, lemon juice, and vanilla extract, blending well.

Gently fold the dressing into the fruit mixture just before serving, ensuring not to squish the fruits.

Transfer to a serving bowl or individual cups and serve immediately.