Strawberry Spinach Salad

I love anything with fresh spinach. I got this from a co-worker, its delish.

1/3 c cider vinegar
3/4 c sugar
2 TBS lemon juice
1 tsp salt
1 c vegetable oil
1/2 small red onion, grated (I use the food chopper)
1 1/2 TBS pops seeds
1 tsp dry mustard
1/2 tsp paprika
1 1/2 lbs fresh spinach, washed and torn into pieces
1 can hearts of palm, drained and chopped
2 c strawberries, stemmed and sliced
1 c chopped walnuts

For the dressing, combine the vinegar, sugar, lemon juice, and salt in a small non-reactive saucepan and heat over medium heat until the sugar dissolves, stirring frequently. Remove pan from heat and let cool to room temperature. When cooled, whisk in the oil, onion, poppy seeds, dry mustard, and paprika until thoroughly combined. Set dressing aside. In a salad bowl, combine the spinach, hearts of palm, strawberries and walnuts. When ready to serve, add some of the dressing, and toss gently. Serve the remaining dressing alongside the salad so diners may add more if desired.