Add the 1 cup water to the Instant Pot. Place steamer basket in pot. Add potatoes and green beans to the steamer basket. Seal lid and set to Manual pressure for 3 minutes. When cycle is complete, quick release the pressure and carefully remove the steamer basket. Pour potatoes and beans into a large bowl.
While potatoes are cooking, place the diced bacon in a skillet over medium heat and cook until crispy. In the final few minutes of cooking, add the red onion. Remove bacon and onion with a slotted spoon and drain on paper towels.
Drain off about half of the bacon grease. To the remaining bacon grease, add dijon and vinegar, whisking well. Cook for 1-2 minutes. Add garlic, salt, pepper, and oil and continue to cook for another 1-2 minutes.
Remove the bacon dressing from heat and pour over potatoes. Season to taste with additional salt and pepper. Garnish with chopped fresh parsley if desired. Serve warm or cold.
For Whole30, look for bacon that does not have any added sugar. Applegate makes a good compliant bacon. For non-Whole30, use bacon of your choice.