Fresh Green Bean Salad

10 ounces grape tomatoes , whole

3 ounces fresh baby spinach, whole leaves (about 2 cups packed)

1 small red onion , halved and thinly sliced

2 (14 ounce) cans hearts of palm or 2 (14 ounce) cans marinated hearts of palm , sliced into 1/2-inch slices

1 lemon, juice of (about 1/4 cup)

1/4 cup balsamic vinegar

1/4 cup olive oil

1/2 teaspoon salt

1/4 teaspoon black pepper

2 tablespoons fresh oregano , minced

2 garlic cloves , minced

2 g Splenda sugar substitute (optional for a sweet taste) or 2 g sugar , to taste (optional for a sweet taste)

feta cheese , to top