Cook snow peas in boiling water to cover 1 minute; drain. Plunge into ice water to stop the cooking process. Cut lengthwise into 1/4-inch strips.
Cut pears into 1/4-inch strips; toss with lemon juice. Cut jicama and spinach into thin strips.
Whisk together vinegar and next 3 ingredients. Gradually add oil, whisking until mixture is well blended. Stir in green onions and basil. Chill 15 minutes.
Combine vegetable strips and pear strips. Drizzle with dressing, tossing to coat; sprinkle with pecans. Serve immediately.