Put the peas in a saucepan with 3 cups water and 1/2 teaspoon salt. Bring to a boil and cook 4 minutes.
Remove from the heat, cover and let sit 1 hour.
Drain, then return to the saucepan with 1 cup fresh water. Bring to a simmer and cook, partially covered, until just al dente, about 10 minutes.
Let cool in the liquid.
Meanwhile, put the rice in another saucepan with 1 1/2 cups water and the garlic. Bring to a simmer, cover and cook 16 minutes.
Remove from the heat and let cool, then fluff with a fork.
Whisk the mustard, vinegar, olive oil, honey, cilantro, 1/2 teaspoon salt and 1 teaspoon pepper in a nonreactive bowl. Adjust the seasoning if necessary.
Drain the peas and toss with the rice in a large bowl.
Add the onion, bell pepper and olives, then add the dressing and toss. Refrigerate until ready to serve.