Source: The Food Lab, page 790

1 small shallot

Mince or grate

3 tbsp balsamic vinegar
1 tbsp soy sauce
4 tsp dijon mustard
1 medium clove garlic
0.5 cup canola oil
0.25 cup extra-virgin olive oil
0.5 tsp salt
0.25 tsp black pepper

Combine everything, shake until emulsified