Japanese Restaurant-Style Salad Dressing

1/2 cup minced onion
1/2 cup peanut oil
1/3 cup rice wine vinegar
2 tablespoons water
2 tablespoons minced fresh ginger root
2 tablespoons minced celery
2 tablespoons ketchup
4 teaspoons soy sauce
2 teaspoons white sugar
2 teaspoons lemon juice
1/2 teaspoon minced garlic
1/2 teaspoon salt
1/4 teaspoon ground black pepper

In a blender, combine the minced onion, peanut oil, rice vinegar, water, ginger, celery, ketchup, soy sauce, sugar, lemon juice, garlic, salt and pepper. Blend on high speed for about 30 seconds or until all of the ingredients are well-pureed.