Julienne the carrots and fennel bulbs with a knife or with a mandoline. Place in a salad bowl with half the chopped fennel fronds and toss to blend. Keep remaining fennel fronds for garnish.
Prepare dressing. Place all ingredients in a mixing bowl and whisk to blend. Taste by dipping a pinch of the salad mix into it. Adjust seasonings as necessary. More horseradish and lime will make the flavor "brighter"; more Sambal Olek will, of course, set your hair on fire.
Add dressing to salad and toss to blend. Garnish with remaining chopped fennel fronds.