Cuban Spinach Strawberries and Mango Salad

Mira K's Cuban co-worker recipe

Spinach (regular or baby)
1 pint strawberries (cleaned/hulled/cut in half)
1 mango (do not use overly ripe ones)

Dressing
1/4 cup oil
1/3 cup vinegar (cider, white wine, or champagne)
1/3 cup sugar
1 cup finely diced shallots (depending on my onion mood, sometimes I use only half a cup)
2 tablespoons sesame seeds
1 tablespoon poppy seeds